Invasive insects and other invasive pests can have significant and negative impacts on agroecosystems and increase the cost of crop production. For example, the pea leaf weevil and cabbage seedpod weevil invaded and established in the prairie region in the past 25 years. Both have affected yield and required insecticide application for management.
Managing invasive alien species, including insects, involves: Preparedness, Prevention, Detection, Response and Recovery.
Preparedness, Prevention, and Detection are important steps that can help to keep invasive species from becoming established. Everyone can help to prevent the invasion of insects by following guidelines to avoid the accidental movement or introduction of insects to Canada.
Similarly, everyone can help with early detection of invasive insects. In the Prairie Region, 12 important insect pests to watch out for are included on posters developed by the Canadian Plant Health Council. The poster is also available in French.
This is the last Insect of the Week post of 2024. Thank you for reading the Insect of the Week series this year!
The wheat stem sawfly, Cephus cinctus, is native to western Canada. Its hosts include species of native grasses as well as rye, barley, and winter wheat. It is most economically damaging to spring wheat and durum wheat in western Canada.
An adult wheat stem sawfly. Picture by Dylan Sjolie, AAFC-Saskatoon.
Adult wheat stem sawfly do not feed; they live for about 10 days and spend that time mating, dispersing to wheat or durum crops, and laying eggs. Larvae are the damaging stage of the wheat stem sawfly life cycle. Larvae feed on pith inside the wheat stems. Because the larvae feed inside the wheat stems, the damage they cause is not obvious or easy to detect.
By feeding inside the host plant stems, wheat stem sawfly can reduce the quality and quantity of the grain produced by their host. In the late summer, the larvae also cut the stems of their host plant when they prepare to overwinter. The cut stems are susceptible to lodging.
European corn borer, Ostrinia nubilalis, is a generalist pest of a variety of crops, including corn, potatoes, beans, sugar beets, tomatoes, quinoa, and millet. European corn borer is an occasional pest of crops in western Canada; as many of its hosts are grown in western Canada, it is important to monitor for European corn borer. In eastern Canada, European corn borer is an important pest and its populations are monitored by the Great Lakes and Maritimes Pest Monitoring Network and by the Réseau d’avertissements phytosanitaires in Quebec.
European corn borer larva and feeding damage on a plant stem. Picture by Jocelyn Smith, University of Guelph.
In western Canada, European corn borer has one generation per year. Adult female moths lay eggs in clusters on the underside of leaves in June, July and August. Larvae can typically be found feeding on leaves starting in July. Larval feeding continues until the larvae reach the fifth instar, which overwinters.
External plant symptoms of European corn borer feeding damage on corn. Picture by Jocelyn Smith, University of Guelph.
Early instar European corn borer larvae eat the leaves of their host plants. As the larvae grow, they tend to begin feeding on the midrib of leaves and on plant stems by tunneling into these plant structures. In corn, the growing larvae can mine into and feed on the corn tassels. Damage to the leaves and stems caused by European corn borer larvae can cause dieback, especially to young plants. Damage to the stems caused by tunneling larvae can weaken the plants, leaving them prone to breakage during storms or in windy conditions. Damage to the stems also interrupts nutrient cycling in infested plants, which can affect the quality and quantity of yield.
European corn borer damage to millet. Note the pile of frass (insect feces) in a pile below the affected millet plant. Picture by John Gavloski, Manitoba Agriculture.
Later instar larvae often begin feeding on the reproductive structures of the host plant: the pods, fruits, or ear shanks. Larval feeding to these structures affects the marketability of the crop; in many crops, including sweet corn and peppers, there is zero tolerance for European corn borer damage.
The Insect Community of Practice, a committee of the Canadian Plant Health Council has developed a harmonized monitoring protocol for European corn borer. This protocol can be used in any of the many crops that European corn borer can infest, not just corn.
Pieris rapae is known as the imported cabbageworm, the cabbage butterfly, and the cabbage white butterfly. Larvae are green and are covered in short, soft hairs, giving them a velvety appearance. The larvae are the damaging stage of the cabbage white butterfly life cycle. The larvae will eat the leaves and pods of canola and related field crops, but cabbage white butterflies are not considered to be an economic pest of canola.
A group of larvae of the imported cabbageworm (a.k.a. cabbage white butterfly) feeding inside a broccoli crown. Picture by Meghan Vankosky, AAFC-Saskatoon.
The larvae of cabbage white butterflies also consume the leaves of cruciferous weeds and vegetables, like broccoli, cabbage, and rutabaga. In vegetables, feeding damage to the leaves results in jagged holes.
A broccoli plant in a backyard garden with jagged holes in the leaves caused by cabbage white butterfly larvae. At least two larvae are also visible in the picture. Picture by Meghan Vankosky, AAFC-Saskatoon.
Larvae can also tunnel into the heads of vegetables, as pictured below. The combination of feeding damage to the heads and build-up of frass (fecal matter) can affect the marketability of vegetables infested with cabbage white butterfly larvae.
A broccoli crown with two holes in the head where larvae of the cabbage white butterfly tunneled into the center of the crown. The larvae pictured above were found feeding inside this broccoli crown. Picture by Meghan Vankosky, AAFC-Saskatoon.
Adult cabbage white butterflies do not damage crops as they feed on nectar. The white butterflies have black-tipped forewings with black spots and are often seen flying around canola and mustard fields and around gardens where cruciferous vegetables are grown. In 2023, cabbage white butterflies were especially numerous in southeastern Saskatchewan in August.
An adult cabbage white butterfly. Picture by David Cappaert, bugwood.org.
Canola flower midge overwinter inside cocoons in the soil and adults usually begin to emerge in late June and can be found until late August, so long as canola flowers are available. There are likely two generations per year, but emergence of adults also seems to be relatively unsynchronized and may not always occur in distinct peaks that align with discrete generations. Canola flower midge adults are not damaging to their host plants. The presence of adult canola flower midge can be detected using pheromone-baited traps.
A canola flower with canola flower midge larvae developing inside. Picture by Jon Williams, AAFC-Saskatoon.
Adult female canola flower midge lay their eggs on developing canola buds before they bloom. The larvae develop in groups inside the flower, resulting in a galled flower that does not produce a pod.
Galled flowers, resulting from larval feeding by canola flower midge on a canola raceme. Picture by Boyd Mori, University of Alberta.
Galled flowers can occur at any point along a canola raceme, with early emerging adults laying eggs on the first flowers to open. The galled flowers tend to remain ‘stuck’ on the raceme, even after the larvae have dropped to the soil to pupate. A monitoring protocol for canola flower midge, based on galled flowers can be used to estimate population densities in canola fields.
A canola raceme with galled flowers (circled), caused by canola flower midge in the field. Picture by Boyd Mori, University of Alberta.
Canola flower midge was described in the scientific literature in a paper published by Mori et al. in 2019, after its identify was confirmed in 2016. There is still a lot to learn about canola flower midge, including its potential to have economic impacts on canola yield.
Please read more about canola flower midge in previous Insect of the Week posts published in 2018 and 2021 or visit the Canola Council of Canada Canola Encyclopedia for more information about canola flower midge.
To the very best of our knowledge, swede midge are NOT currently present in western Canada.
Adult and larval swede midge on a growing point of a canola plant; note the characteristic purpling of the infested growing point. Picture by Jon Williams, AAFC-Saskatoon.
Every year, the Prairie Pest Monitoring Network coordinates a pheromone-based monitoring program for swede midge because of the high risk that swede midge poses to the canola industry in western Canada. Swede midge is also a threat to the vegetable industry in western Canada, as it can use broccoli, cabbage, cauliflower, and other crucifer vegetables as a host.
Adult swede midge do not damage canola or crucifer vegetables, but females lay eggs on the growing points of the plant. When eggs are laid on the florets of canola, some flowers on the raceme may develop normally, but the others become ‘fused’ together as a result of swede midge larval feeding.
Flower buds ‘fused’ together on a floret, the result of infestation by swede midge. Picture by Jon Williams, AAFC-Saskatoon.
Female swede midge can also lay eggs where new racemes or branches grow off the main stem of canola plants. In this situation, larval feeding stops the growth of the new raceme, leaving a stunted raceme with crumpled leaves that often turn purple.
Crumpled and purple-coloured new growth on a canola plant, as in the circled part of the picture, is a symptom of infestation by swede midge. Picture by Meghan Vankosky, AAFC-Saskatoon.
In vegetable crops like broccoli, cauliflower, and cabbage, larval feeding on the growing point of the plant prevents development of the harvestable heads. Very high yield losses have been observed in eastern Canada and the eastern United States in vegetable crops because of swede midge damage.
So far, swede midge is not an established pest in western Canada and we have not found it in pheromone traps in 10+ years of monitoring in Alberta, Saskatchewan, or Manitoba. But, swede midge is slowly moving farther and farther west in the United States. To protect the canola and vegetable industries in western Canada, it is very important to be vigilant and continue to monitor for swede midge.
If you find damage on canola or crucifer vegetable crops that looks like it could be swede midge damage, please report it. You can email meghan.vankosky@agr.gc.ca with pictures or questions.
The Lygus bug pest complex includes at least 5 species, including the tarnished plant bug (Lygus lineolaris), Lygus keltoni, and Lygus borealis. Lygus bugs have an upside down triangle on their backs and adults are about 5-6 mm long; their colour varies depending on the species and their stage of development. Lygus bugs have a fairly wide host range, but canola, soybean and alfalfa are prone to yield losses resulting from Lygus feeding damage.
An adult Lygus bug, with the characteristic triangle on the back. Picture by AAFC-Saskatoon. Lygus nymphs of different instars and an adult Lygus bug. Pictures by Hector Carcamo, AAFC-Lethbridge.
The nymphs and adults use piercing and sucking mouthparts to drink from their host plants. They prefer to feed on new growth and reproductive tissues, as these are more nutrient-rich than other plant structures. Feeding by Lygus bugs can result in bud-blasting, where developing buds or flowers do not continue to develop and drop from the plant. If Lygus bugs feed on developing seeds, the seeds become shriveled, reducing yield quality and quantity. Watch for circular, black scars on canola pods, as these are an indicator that Lygus bugs has been feeding on canola pods, and probably on the seeds inside the pods.
Top: A canola raceme with bud blasting symptoms typical of Lygus feeding injury. Bottom: Canola seeds damaged by Lygus feeding (left, middle) and healthy canola seeds (right). All pictures by R.A. Butts, AAFC-Lethbridge.
In addition to direct yield losses due to Lygus feeding damage, the wounds left by their mouthparts make plant tissues vulnerable to infection by pathogens. Because Lyugs bugs inject digestive enzymes into the plant to help break down plant tissues for consumption, they can also vector plant diseases.
Use a sweep net to scout for Lygus bugs in canola and alfalfa crops. The PPMN has a monitoring protocol available here.
In canola, scout as flowering is complete and pods are beginning to ripen. Take 10 sweeps at 15 locations in the field and estimate the number of lygus nymphs and adults per sweep. Recent research suggests that the economic threshold to avoid yield loss in canola is 2-3 Lygus bugs per sweep; check out the Canola Council of Canada, Manitoba Agriculture, and Alberta Agriculture and IrrigationLygus pages for more information about Lygus bugs and economic thresholds in canola.
In alfalfa, scout at the start of the bud stage by taking 5 sweeps in at least 15 locations per field and estimating the number of Lygus nymphs and adults per sweep. In seed alfalfa fields, the economic threshold is 8 Lygus per sweep in at least 40 sweeps.
For more information about Lygus bugs, visit previous Insect of the Week articles and find the Lygus page in Field Crop and Forage Pests and their Natural Enemies in Western Canada, available in English and in French. SaskPulse also recently published an overview of Lygus impacts on pulse crops written by Jennifer Bogdan.
Cabbage seedpod weevil, Ceutorhynchus obstrictus, is an invasive alien insect. Cabbage seedpod weevil is present in Alberta, Saskatchewan and Manitoba but it has not yet been detected in the Peace River region. Both the adult and larval stages of cabbage seedpod weevil feed on canola, brown mustard, and wild mustard. Feeding by the larvae generally has a greater impact on crop yields than feeding by the adults.
A dead adult cabbage seedpod weevil, posed for a picture by Jon Williams, AAFC-Saskatoon.
Cabbage seedpod weevil larval feeding results in direct yield loss because the developing larvae consume developing canola and brown mustard seeds inside the pods. Each larva can eat up to 5 seeds during its development. In addition to the direct yield loss caused by the larvae, pods infested by cabbage seedpod weevil are more likely to shatter during harvest and are prone to secondary infection by fungal pathogens.
A cabbage seedpod weevil larva inside a canola pod, where it developed by consuming canola seeds. Picture by AAFC.
Adult cabbage seedpod weevil will feed on a variety of brassica species, both crops and weeds, but does not use yellow mustard as a host plant. In spring, adult cabbage seedpod weevil can be found feeding in patches of flix weed, hoary cress, stinkweed, and volunteer canola. The adults then disperse into canola and brown mustard crops, where they eat flower buds and flowers. This feeding damage can result in bud-blasting, but does not typically impact crop yields. The new generation of cabbage seedpod weevil adults that emerge in late summer can also feed on pods before the crops are harvested.
Exit holes in canola pods that were chewed by cabbage seedpod weevil larvae. Larvae exit the pods to pupate in the soil once larval development is completed. Picture by AAFC.
Scout for adult cabbage seedpod weevil as they disperse into canola fields and prepare to lay eggs. When scouting, take ten 180° sweeps at ten locations in the field. Count the adult weevils after each set of 10 sweeps and calculate the average number of adult cabbage seedpod weevil per sweep. Carcamo et al. published new research about cabbage seedpod weevil in 2019, where they found that the economic threshold for cabbage seedpod weevil is 2.5-4 adult weevils per sweep.
For more information about cabbage seedpod weevil, visit previous Insect of the Week articles and find the cabbage seedpod weevil page in Field Crop and Forage Pests and their Natural Enemies in Western Canada, available in English and in French.
Wheat midge, Sitodiplosis mosellana, is an important pest of spring wheat, winter wheat, durum wheat and triticale. Spring rye can also experience some damage from wheat midge. Adult wheat midge do not damage their host plant, but do lay eggs that give rise to the damaging larval stage.
Wheat midge larvae feed on the outside of wheat kernels. Larval feeding results in shrunken, shriveled, and/or cracked kernels. Larval feeding can also cause kernel development to be aborted.
Feeding damage caused by larval wheat midge reduces grain yield and the quality of the harvested grains. Grains with wheat midge damage are typically downgraded at the grain elevator.
Wheat midge damage to the kernels is not easy to detect and can go unnoticed. Therefore, scouting for adult wheat midge is necessary to determine if foliar insecticides may be needed to prevent female wheat midge from laying eggs. Scout for adults in the evenings, daily during the susceptible plant stage. Calm evenings are best for scouting. Count the adults on 4-5 wheat heads at 5 locations in the crop to estimate midge per wheat head. Economic thresholds are:
During bertha armyworm outbreaks, canola and mustard crops typically experience the most damage and highest economic losses. However, bertha armyworm also eat alfalfa, peas, quinoa, flax, potatoes, and other crop and weed plants. Adult moths do not damage crops. Larvae consume green plant tissues using their chewing mouthparts.
A canola field stripped of leaves and with damage to pods following a severe infestation of bertha armyworm in Manitoba. Picture by John Gavloski, Manitoba Agriculture.
Bertha armyworm larvae are cause for concern when they occur in high numbers when canola pods are developing and maturing. This is because ‘mature’ bertha armyworm larvae (e.g., 5th and 6th instars) will start eating developing canola pods. Pod damage includes debarking, which can result in pod shatter before or during harvest. Bertha armyworm larvae can also directly consume the developing seeds. Bertha armyworm larvae can also clip flowers and bolls off of flax plants.
A bertha armyworm caterpillar in the process of feeding on a canola pod. Picture by John Gavloski, Manitoba Agriculture. Bertha armyworm damage, caused by larvae, to canola pods. Picture by Shelley Barkley, Alberta Agriculture and Irrigation.
The Prairie Pest Monitoring Network, Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture and Manitoba Agriculture coordinate an annual monitoring program for bertha armyworm using pheromone traps. The 2024 monitoring season started the week of June 10 and will continue until late July. Thank you to all of the volunteers across the prairies who are hosting bertha armyworm pheromone traps!
The number of bertha armyworm moths captured in the pheromone traps serves as an estimate of local risk. Watch for information about the bertha armyworm monitoring program from the PPMN Weekly Updates and the provincial insect updates. If trap catches indicate possible risk, then scout canola crops for larvae using the bertha armyworm monitoring protocol found on the PPMN Protocol page. Information to calculate economic thresholds can also be found in the monitoring protocol.
The life cycle of bertha armyworm: A) eggs, B) larval stage, C) pupal stage, and D) adult stage. The larval stage is the only stage that actively damages crops. All pictures by Jon Williams, AAFC-Saskatoon.
Diamondback moth larvae have voracious appetites for canola, mustard, flix weed, and vegetables including broccoli, brussels sprouts, cauliflower, and kale. They are specialists of plants in the family Brassicaceae (formerly Cruciferae).
When diamondback moth larvae first hatch, they are very small and tunnel inside the leaves to eat, resulting in damage that looks like shot-holes and leaf mines.
The life cycle of diamondback moth and damage characteristic of B) first and second instar larvae that tunnel and mine leaves, often leaving ‘shot-hole’ damage, and C) third and fourth instar larvae that can eat entire leaves, except for the leaf veins. All pictures taken by Jon Williams, AAFC-Saskatoon.
Third and fourth instar larvae are larger and can consume entire leaves, leaving just the leaf veins. Larvae will also eat the buds, flowers and developing pods. Later in the growing season, as canola matures, diamondback moth larvae can strip the pods of any remaining green tissues.
Damage caused to a canola plant in a colony of diamondback moth maintained at AAFC-Saskatoon. This is an extreme example of the capacity of diamondback moth larvae to strip all green material from the stems, leaving a skeletonized plant with a frosted appearance.The picture also shows how frass (fecal material) can accumulate on the remaining plant tissues. Picture by Meghan Vankosky, AAFC-Saskatoon.
In addition to feeding damage, frass (or fecal material) excreted by diamondback moth larvae can affect the marketability and the quality of crucifer vegetables like broccoli, cauliflower, cabbage and brussels sprouts by contaminating or staining the developing vegetable heads.
Remember that the diamondback moth can have multiple generations per year and that each generation takes about 18-20 days (but can be shorter or longer depending on temperature). With each generation, there is potential for the population density to grow and exceed economic thresholds. Scout for diamondback moth by examining plants for larvae and estimate the number of larvae per m2 to determine if the population is nearing or has exceeded the economic threshold.
In canola, the economic threshold for diamondback moth larvae is 100-150 larvae/m2 when canola plants are immature and flowering. The threshold is 200-300 larvae/m2 when canola plants are mature.
Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
Grasshoppers have mouthparts designed for chewing. Grasshopper nymphs and adults efficiently consume host plant foliage using their chewing mouthparts. During serious outbreaks, grasshoppers can strip all leafy material off the host plant stems and can also be found eating the leaves on shrubs and trees.
A sweetclover plant stripped of all leaves by grasshoppers. Picture taken by Meghan Vankosky, AAFC-Saskatoon in southern Saskatchewan in late summer 2023.
Feeding damage caused by different grasshopper stages on the leaves of cereal plants. Two-striped grasshoppers were common at this location, near Langham, Saskatchewan in July 2023. Picture by Meghan Vankosky, AAFC-Saskatoon.
The four primary pest grasshopper species differ slightly in terms of their preferred hosts. For example, the clearwinged grasshopper (Camnula pellucida) prefers cereals and some succulent grasses, but tends to avoid broad-leaf species. The two-striped grasshopper tends to show a preference for more ‘lush’ hosts, including broad-leaf species like alfalfa and various pulse crops, as well as cereals and grasses.
The migratory grasshopper has a wide host range and can clip pods and grain heads on maturing crops to find green tissues to eat.
Grasshopper feeding damage on wheat seedlings inside a demonstration cage. Picture by Meghan Vankosky, AAFC-Saskatoon.
Cereal leaf beetle larvae eat the upper surface of leaves, leaving behind ‘windows’ of missing foliage that can look like white or yellow stripes on the leaves. Wheat is the preferred host of adult and larval cereal leaf beetle, but this pest will also consume barley, oats, rye, millet, wild oats, and other grasses.
In this picture, we see evidence of larval cereal leaf beetle feeding where green material is stripped from the leaf surface. We also see a female Tetrastichus julis parasitoid in the process of parasitizing a cereal leaf beetle larva! Picture by Emily Lemke and Karen Shamash, AAFC-Lethbridge.
Feeding damage caused by adult cereal leaf beetle does not typically result in yield loss to the crop. Rather, feeding damage caused by the larvae, especially to the flag leaf, results in lost yield and reduced crop quality.
In western Canada researchers expected cereal leaf beetle to become a widespread and problematic pest. This prediction has thankfully not yet come true, probably mostly due to the efficacy of an introduced parasitoid, Tetrastichus julis. Learn more about the parasitoid in one of the 2023 Insect of the Week posts!
The pea leaf weevil is now present in Alberta, Saskatchewan, and Manitoba. Learn more about the biology of the pea leaf weevil here and about its distribution across western Canada here.
An adult pea leaf weevil, Sitona lineatus, feeding along the margin of a field pea plant, leaving behind a ‘u’-shaped feeding notch. Picture by Jon Williams, AAFC.
This insect causes damage to field pea and faba bean crops during the adult stage and during larval development. Adult pea leaf weevil eat the foliage of their host plants, leaving ‘u’-shaped notches along the edge of the leaves.
A field pea plant with pea leaf weevil feeding damage. Picture by Meghan Vankosky, AAFC.
Adult pea leaf weevil will also feed on a variety of other legume and pulse crops, including alfalfa, chickpea, and soybean. Most adult feeding on these hosts takes place in early spring before pea and faba seedlings emerge, and again after peas and fabas have been harvested in summer and early fall.
Faba bean plants with adult pea leaf weevil feeding damage. Picture by Meghan Vankosky, AAFC.
Pea leaf weevil larvae damage the nitrogen-fixing root nodules on field pea and faba bean plants.
A root nodule from a field pea plant with damage caused by pea leaf weevil larvae. Areas with damage appear a dark pink colour. Picture by Meghan Vankosky, AAFC.
Wireworms are the larval stage of click beetles from the family Elateridae. Click beetles, the adult stage, do not cause damage to crops.
A cereal field with patchy seedling emergence and stand establishment due to wireworm infestation. Picture by Dr. Haley Catton (AAFC, Lethbridge).
Similar to cutworms, bare patches in a field can be an early and obvious sign of wireworm infestation in the spring. Patchy crop emergence, as pictured above, results when wireworms consume germinating seeds or feed on the roots and stems of young seedlings, as pictured below.
Wireworm feeding damage on a faba bean seedling. Picture by Chris Baan.
Wireworms live in the soil, where it can take 4 or more years to complete larval development. In the soil, wireworms feed on germinating seeds and the roots of a wide variety of prairie field crops including cereals, pulses, oilseeds, and vegetables including potato and carrots. Damage to root vegetables can result in unmarketable produce.
Carrots with damage caused by wireworms. Picture by Dr. Haley Catton (AAFC, Lethbridge).
It is common to use baits to scout for wireworms. Baits, consisting of cut potato pieces or soaked mixtures of oatmeal and other seeds, should be buried 5-10 cm deep at 10 or more locations in unplanted fields in the spring to determine if wireworms are present before planting. Leave the baits for 2 weeks and then dig up the baits to look for wireworms. In fields with patchy seedling emergence, soil sampling can be used to look for wireworm larvae and to determine if the damage is being caused by wireworms or by another pest (like cutworms).
The striped flea beetle and crucifer flea beetle are two of the most important pests of canola (and other Brassicaceae) in western Canada, especially early in the growing season. Adult flea beetles spend the winter sheltered under leaf litter, generally along field margins. In spring, adults disperse into crop fields to eat, mate, and lay eggs. For more information about the biology of flea beetles, click here.
‘Shot hole’ feeding damage caused by flea beetles on the cotyledons and first true leaves of a canola seedling. Picture by Ruwandi Andrahennadi, AAFC-Saskatoon.
Flea beetle feeding damage has a characteristic ‘shot-hole’ appearance on the cotyledons, as pictured above. Flea beetle feeding damage can also be observed on the first true leaves (also with a ‘shot-hole’ appearance) and on the stem and growing point of the seedlings.
A striped flea beetle feeding on the stem of a leaf. Excessive feeding on the stems of young seedlings can cause stems to break or plants to wilt and if severe, could kill the seedlings. Picture by Ruwandi Andrahennadi, AAFC-Saskatoon.
To scout for flea beetles, examine seedlings for the characteristic ‘shot-hole’ feeding, starting at the field margin. Scout often, as flea beetles can move into fields quickly. The action threshold for applying foliar insecticides for flea beetle is met when 25% of the cotyledon area has been eaten. Visit the Canola Council of Canada Canola Encyclopedia for tools to help estimate defoliation by flea beetles.
Flea beetles can also cause damage later in the summer when the new generation of flea beetles emerges and are looking for food before winter. The feeding damage looks the same as the damage in the spring. High densities of flea beetles feeding on plants late in the season can cause plants to ripen prematurely and feeding damage on pods can contribute to yield loss via pod shatter.
Drying and desiccated leaves of rutabaga in late summer at Outlook, Saskatchewan, following a severe infestation of new generation flea beetles. Picture by Meghan Vankosky, AAFC-Saskatoon.
Welcome back to the Prairie Pest Monitoring Network Insect of the Week! In 2024, the Insect of the Week theme is “What is eating my crop?” All of the Insect of the Week posts will focus on the damage that insects pests cause to their host plants. In many cases, insect feeding damage is characteristic of certain pest species and can help to identify the insect pest or narrow down the list of suspects.
Cutworm Damage
Numerous species of cutworms can cause economic damage to crops in western Canada, including pale western cutworm (Agriotis orthogonia) and redbacked cutworm (Euxoa orchrogaster). Because there are so many species of cutworms, cutworms are an important pest complex, with quite diverse life histories, preferred host plants, and damage symptoms.
All cutworm species undergo complete metamorphosis during their lifetime, progressing through four stages: egg, larva, pupa, and adult. The larval stage is responsible for damage to crops and forage plants. Several cutworm species overwinter as larvae in western Canada, including army cutworm (Euxoa auxiliaris), dusky cutworm (Agrotis venerabilis), and glassy cutworm (Apamea devastator). Therefore, there might already be larval feeding activity happening where these species are present.
A cereal field with patchy crop establishment due to cutworm infestation (picture courtesy of AAFC)
There are three primary types of feeding behaviour used by larval cutworms:
1) Subterranean larval feeding, where larvae cut the main stem and consume the foliage by pulling it underground. These larvae are almost never seen out of the soil. The glassy cutworm is an example of a subterranean cutworm. Bare patches in crops, as pictured above, can be indicative of larval feeding by subterranean cutworms.
2) Defoliation by above-ground and surface-feeding larvae that feed on foliage at night but spend the day hiding under leaf litter or under the soil. The army cutworm is a typical above-ground feeding cutworm; late-instar larvae will eat entire leaves, while young larvae feed along the leaf margins. Damage typical of the black cutworm (Agrotis ipsilon) includes irregularly shaped holes in the leaves and stem cutting.
3) Defoliation by climbing cutworms, where the main stem is not usually damaged but is used by larvae to reach the leaves. Damage to the foliage is similar to that caused by above-ground or surface-feeding cutworms.
For more information about cutworms and the damage that they do, please check out Cutworm Pests of Crops on the Canadian Prairies, available in English and in French. You can also read about cutworms in Field Crop and Forage Pests and Their Natural Enemies in Western Canada (in English or in French).
Bracon cephi and Bracon lissogaster are the primary parasitoids that attack wheat stem sawfly and help to regulate wheat stem sawfly populations in North America. These closely related parasitoid species are described as idiobiont ectoparasitoids. The parasitoid larva, after hatching from an egg laid on the surface of the wheat stem sawfly larva, consume the entire host except for the host’s head capsule and exoskeleton. Both Bracon species complete their development and pupate inside the wheat stem. Their pupae are generally found inside the exoskeleton or beside the remnants of their consumed wheat stem sawfly host. There are two generations of B. cephi and B. lissogaster per year. The first generation completes its lifecycle then exits the wheat stem to locate a new host to parasitize. The second generation overwinters within the wheat stem.
Adult Bracon cephi parasitoid, pictured inside a vial (hence the artistic effect!) by Dylan Sjolie, AAFC-Saskatoon.
Braconcephi and B. lissogaster are similar in appearance. The wasps are typically 2-15 mm long and brown in colour. They have a narrow waist connecting the abdomen to the thorax and the combined length of head plus thorax is equal to the length of the abdomen. These parasitoid wasps have long antennae and two pairs of transparent wings. Females have a noticeable ovipositor protruding from the end of the abdomen.
Parasitoid population dynamics and efficacy are influenced by crop management practices. Parasitoids can be conserved by increasing the height of stubble when harvesting and reducing insecticide applications in grass ditches where natural enemies of the wheat stem sawfly are abundant.
For more pictures and information about the natural enemies of the wheat stem sawfly, check out our past Insect of the Week post about Bracon cephi!
Native to North America, the wheat stem sawfly is an economic pest depending on spring and durum wheat as its main crop hosts. These insects also target winter wheat, rye, grain corn and barley, in addition to feeding on native grass species. It is interesting to note that wheat stem sawflies do not feed on oat crops, as oats are toxic to wheat stem sawfly.
An adult wheat stem sawfly. Picture by Dylan Sjolie, AAFC-Saskatoon.
Wheat stem sawfly larvae feed on pith inside the stems of their host plant. Their feeding activity affects crop yield and quality. As infested host plants mature, the larvae travel down the stem to its base, where “V” shaped notches are cut into the stem a little above ground level. These notches leave plants vulnerable to collapsing or lodging, especially during wind events. Because wheat stem sawflies also breed and develop on native grass species, economic damage tends to be most prevalent around crop margins where native and agricultural plants are found close together.
An adult wheat stem sawfly. Picture by Dylan Sjolie, AAFC-Saskatoon.
Adult wheat stem sawflies are 8–13 mm long with a wasp-like resemblance, due to their black body and yellow legs. Females have an egg-laying organ (an ovipositor) that extends from their abdomen. When resting on plant stems, these insects will point their heads downward. Mature larvae are 13 mm long and resemble whitish worms with brown heads.
Aphidius spp. parasitoid wasps (Hymenoptera: Aphidiidae) are important natural enemies of aphids. Their hosts include over 40 aphid species! Female parasitoids lay individual eggs inside aphid nymphs. After hatching, the parasitoid larva consumes its host, eventually killing it. The parasitoid pupates inside the dead or mummified aphid before a new adult parasitoid emerges. New generation adult parasitoids chew a hole in the mummified aphid to exit and immediately search for new aphid hosts.
Aphid mummies are the result of parasitism by Aphidius spp. parasitoids. Picture by Jennifer Otani, AAFC-Beaverlodge Research Farm.
Aphid mummies look bloated and discoloured compared to healthy adult aphids. Parasitism rates can be estimated by counting the number of aphid mummies on five host plants at five locations within a field.
The English grain aphid (Sitobion avenae) is a pest that infests wheat, barley, oat, rye, timothy, and canaryseed. Adults are 1.5 to 2 mm in size and yellow-green to reddish-brown with black antennae, leg joints, and cornicles. Nymphs are similar in appearance, but smaller in size.
Adults and nymphs of the English grain aphid. Picture credit: Jennifer Otani, AAFC-Beaverlodge.
Aphids are typically found on the heads of cereal crops, where they feed on the ripening kernels. Feeding damage results in shriveled kernels and leaf discoloration. Severe infestations result in large visible bronze or brown patches in the field. English grain aphids produce honeydew, a sugary liquid waste, that can promote the infestation and growth of saprophytic and pathogenic fungi on cereal heads. This aphid is also a vector for barley dwarf virus, which can severely stunt plants and prevent heading.
English grain aphids on a cereal head. Picture credit: Jennifer Otani, AAFC-Beaverlodge.
The economic threshold for English grain aphids in spring wheat in western Canada is 12-15 aphids per head prior to the soft dough stage. The number of aphids per head should be recorded on 20 tillers at five different spots scattered throughout the field to ensure an accurate estimate of their population density. Scouting should occur from June until the soft-dough stage is reached. Early seeding may allow crops to move past susceptible stages before aphid populations reach damaging thresholds and reduce risk for barley yellow dwarf virus.
This week, our insects of the week are the natural enemies of diamondback moth found on the Prairies! Four important parasitoids attack this pest: Diadegma insulare, Diadromus subtilicornis, Microplitis plutellae, and Trichogramma praetiosum.
A pupa of the parasitoid Diadegma insulare inside its cocoon. Picture credit: Andrea Brauner, AAFC.
Some of these species (like Diadegma insulare) follow diamondback moth on its yearly migration from the southern United States and some (like Micropletis plutellae) overwinter in Canada and can help with early-season control. These small, dark colored wasps occasionally completely control diamondback moth outbreaks in Canada!
Parasitoids of diamondback moth. On the left: Diadegma insulare. On the right: Microplitis plutellae. Both pictures taken by Amanda Jorgensen, AAFC-Beaverlodge Research Farm.
The four parasitoid species attack during different stages of the diamondback moth lifecycle. Diadegma and Micropletis parasitoids attack larval diamondback moth. Trichogramma and Diadromus species attack the prepupal and pupal stages.
A female Diadromus parasitoid preparing to parasitize a diamondback moth pupa. Picture credit: Andrea Brauner, AAFC.
There is a long list of other wasp species that have been found to parasitize diamondback moth larvae to a lesser extent. Hoverfly larvae, yellowjacket wasps, lacewings, plant bugs, pirate bugs, beetles, spiders and birds also prey on diamondback moth larvae.
The diamondback moth (Plutella xylostella) is an invasive species that migrates northward to the Canadian Prairies on wind currents from infested regions in the USA. Upon arrival, migrant diamondback moths begin to reproduce, resulting in non-migrant populations that may have three or four generations on the prairies during the growing season. The time required for diamondback moth to complete a generation gets shorter when temperatures are warm. In warmer years, diamondback moth populations can build up relatively quickly, increasing their chances of causing economic damage to crops where populations are present. Host plants of diamondback moth include canola, mustard and other cruciferous vegetables and weeds.
A diamondback moth pupa inside a cocoon on a canola leaf. Picture credit: Jonathon Williams, AAFC-Saskatoon.
Diamondback moths lay their eggs on leaves. Hatchling larvae emerge and tunnel into the leaves, later moving to the surface to feed. Damage first appears as shot holes but eventually expands until the leaves are skeletonized, leaving only the leaf veins. Larvae also feed on flowers and strip the surface of developing pods and stems. Larval damage lowers seed quality and crop yield of canola and can affect the marketability of crucifer vegetables.
The lifecycle of diamondback moth: A) eggs, B) early instar larva with damage typical of this life stage, C) late instar larva on a skeletonized leaf, D) pupa, and E) adult moth. All pictures taken by Jonathon Williams, AAFC-Saskatoon.
Adult moths measure 12 millimeters long with an 18-20 millimeter wingspan. At rest, their forewings form a diamond-shaped pattern along the mid-line. Mature larvae are 8-millimetre-long green caterpillars. Their terminal prolegs extend backwards, resembling a fork. When disturbed, caterpillars drop towards the ground on a silken thread to avoid harm.
Macroglenes penetrans is a beneficial parasitoid wasp from the family Pteromalidae. It is an important natural enemy of wheat midge. This small, black wasp can be seen emerging in large numbers from wheat stubble shortly after wheat midge adults are first sighted. This means that often they are emerging into canola fields and then have to disperse to find wheat fields where their hosts are active. Macroglenes penetrans is a parasitoid that lives inside the wheat midge larva and overwinters within the wheat midge larval cocoon. In the spring, the parasitoid larva develops to emerge from the wheat midge cocoon buried in the soil and then the adult parasitoid seeks out wheat midge eggs.
A very small adult Macroglenes penetrans on a wheat head. Picture credit: Shelby Dufton, AAFC Beaverlodge Research Farm.
Macroglenes penetrans is an important part of wheat midge management – parasitism rates can reach upwards of 70% of the wheat midge population! The numbers of this parasitoid overwintering inside wheat midge cocoons are counted during the fall soil core survey, so that the survey map only includes counts of non-parasitized wheat midge.
The cereal leaf beetle larvae you see in wheat fields may be full of this week’s Insect of the Week, Tetrastichus julis. This parasitoid wasp is an important natural enemy of cereal leaf beetle. Adult T. julis lay their eggs inside cereal leaf beetle larvae, leaving about five eggs to consume the beetle from the inside out. Adult parasitoids feed on nectar and aphid honeydew.
A Tetrastichus julis female in the process of parasitizing a cereal leaf beetle larva, sitting on a wheat leaf with cereal leaf beetle feeding damage. Picture credit: Emily Lemke and Karen Shamash, AAFC-Lethbridge.
Mature T. julis larvae overwinter in infested cereal leaf beetle cocoons and emerge in spring to lay more eggs in cereal leaf beetle larvae. Where T. julis has become established, it can reduce cereal leaf beetle populations by 40 – 90%, preventing yield loss without using pesticides. See also the factsheet, Biological Control at its Best, Using the T. julis Wasp to Control the Cereal Leaf Beetle (en français).
AAFC researchers have assisted T. julis in establishing and spreading to help control cereal leaf beetle populations in the Canadian prairies! Reducing the use of insecticides (if possible), leaving refuge areas, and reducing tillage can all help protect populations of this valuable parasitoid in areas where they are already established in a field.
Now is the time to get out and scout for wheat midge!
Wheat midge are small, orange, fragile-looking flies that attack members of the grass family including barley, couch grass, wheat grass, triticale, and spring rye, though their preferred host is wheat.
Adult wheat midge. Picture credit: Shelby Dufton and Amanda Jorgensen, both of AAFC-Beaverlodge.
Adults emerge from mid-June through mid-July and typically coincide with wheat head development and flowering. Wheat midge remain in the humid crop canopy throughout the day and emerge on calm, warm evenings to mate and lay eggs. Eggs are laid singly or in groups of three to five on wheat kernels prior to flowering.
Adult wheat midge. Picture credit: Shelby Dufton and Amanda Jorgensen, both of AAFC-Beaverlodge.
Upon hatching, larvae crawl to developing kernels and feed for two to three weeks. Larval feeding damage results in shriveled, misshapen, cracked, or distorted kernels. Kernels must be inspected within the glume, as damage may not be readily apparent at a glance. Lost or damaged kernels from feeding result in lower crop yield and quality. The Canadian Grain Commission allows midge damage between two and five percent prior to impacting the assigned grade.
Wheat midge larva on a damaged wheat kernel. Picture credit: Amanda Jorgensen, AAFC-Beaverlodge.
After feeding, larvae remain inside the heads until rain or a moisture event occurs, at which point they drop to the soil, bury themselves, and form a cocoon to overwinter. In the spring, if moisture and temperature requirements are met, larvae leave their cocoons and return to the soil surface, pupating for a period of two weeks.
Wheat fields should be inspected for wheat midge in late June and early July, as wheat heads emerge, and females are laying eggs on the developing heads. Scouting should occur in the evening (after 8:30 PM) on calm, warm (15 ˚C) evenings. The number of adults should be counted on four to five wheat heads in three or four locations. Insecticide applications should be considered if economic thresholds are met. To maintain optimum grain grade, the economic threshold is one adult wheat midge per eight to ten heads during susceptible stages (wheat head emergence up until flowering). To prevent yield loss, the economic threshold is one adult wheat midge per four to five heads.
Varieties of midge tolerant wheat are available to help manage this pest! More information on these can be found at www.midgetolerantwheat.ca.
Are there any natural enemies that stand up to wheat midge? Yes! The parasitoids will be featured in an upcoming issue of Insect of the Week.
The cereal leaf beetle (Oulema melanopus) is an invasive insect pest that feeds on oat, barley, corn, rye, triticale, reed canary grass, ryegrass, fescue, wild oat, and millet, though wheat is their preferred host. Originally from Europe, it is now found in most cereal production areas in North America. The cereal leaf beetle can be found in parts of Manitoba, Saskatchewan, and Alberta.
Adult cereal leaf beetle. Photo credit: Boris Loboda.
Adult cereal leaf beetles are about 6 mm long and bear striking coloration with an orange-red thorax, yellow-orange legs, and a metallic blue head and wing covers. Adults overwinter in field debris in the fall, typically emerging in mid-April to May in the Canadian prairies to feed and lay their eggs. Cereal leaf beetle eggs are laid singly or in clusters of two or three along upper leaf surfaces, close to the margins or mid-rib. Initially appearing bright yellow, eggs darken to orange-brown and then black before hatching.
Cereal leaf beetle larva. Photo credit: Dr. John Gavloski
Larvae are the most damaging stage of this insect, feeding on upper leaf surfaces. Larval damage appears in pale lines similar in appearance to window-panes. Severe damage is similar to frost damage, where the leaves appear white and can also be mistaken for slug damage. Larvae are yellow in color with a brown head but may appear black like an oil droplet. Black coloration results from a defense mechanism, where larvae smear themselves with a fecal coating to mask their vibrant coloration and reduce predation. After feeding for 10 to 14 days, larvae drop to the soil, entering a pre-pupal and then pupal stage. Larvae pupate below the soil near the host plant’s roots for three weeks, after which they emerge as adults to feed and move to overwintering sites.
Cereal leaf beetle damage to a cereal crop. Photo credit: Bob Hammon, Colorado State University, bugwood.org
Monitoring for this pest should first occur in the spring, when producers should be on the lookout for adults emerging to feed. Scouting continues throughout the spring and summer, before and during the boot stage to assess cereal leaf beetle populations. Egg and larval scouting should be conducted at 5 to 10 random sites throughout the field, at least three meters from the edge. 10 consecutive plants should be inspected at each location, with the number of eggs and larvae counted per plant (before tillering) or per stem (after tillering). Following this, the average number of eggs and larvae is calculated per plant. Economic thresholds have not been established in Canada but have been established for Montana and North Dakota.
Tune in next week to learn about the cereal leaf beetle’s natural enemy – Tetrastichus julis!
Strawberry blossom weevil (Anthonomus rubi), a recent invader of the Fraser Valley of British Columbia (BC), has been busy clipping buds this spring in strawberry and raspberry fields. This weevil was first spotted in raspberries in Abbotsford, BC in 2019. Native to Europe, Asia, and parts of North Africa, this weevil is now established in the Fraser Valley of BC and northwestern Washington state. It has not yet been found in the prairie provinces.
Damage to strawberry buds from the strawberry blossom weevil. Photo credit: Michelle Franklin, AAFC-Agassiz.
Different from many of the nocturnal root feeding weevils that damage roots and stunt plant growth in berries, strawberry blossom weevil is active during the day. It is small (2-3 mm long) with a small white patch of scales on the scutellum (back) and a long slender rostrum (snout). The female weevil is the main source of damage, as she deposits her eggs inside of green developing buds. She first chews a hole in the bud and then turns around and lays an egg inside, after which she clips the stem below.
A female strawberry blossom weevil laying an egg into a Himalayan blackberry bud. Photo credit: Warren Wong.
Typically a single c-shaped larvae develops inside of a bud. The larvae then pupates and the adult weevil emerges from the bud by chewing an exit hole.
A strawberry blossom weevil larva, about 2.5 mm long, inside a berry bud. Photo credit: Warren Wong.
We are currently investigating the impact of this new weevil on strawberry and raspberry crops in the Fraser Valley of BC. Reports from its native range in Europe indicate that bud losses associated with strawberry blossom weevil range widely from 5 to 90% and yield losses over 60% have been reported. Despite the name, strawberry blossom weevil uses a wide range of host plants in the family Rosaceae – including the invasive Himalayan blackberry and ornamental plants such as rose and potentilla. The United States Department of Agriculture Animal and Plant Health Inspection Service (APHIS) put a Federal Order in place in September 2021 and continues to require a phytosanitary certificate to move Fragaria, Rubus, and Rosa plants from Canada into the USA (Federal Order DA-2021-25).
We need your help surveying for this pest! Although strawberry blossom weevil has not been detected beyond the Fraser Valley of BC, we are continuing a nation-wide survey in summer 2023 for this pest. Adult weevils naturally drop when disturbed so they can be detected by a method called beat sampling – where plants are tapped from above and weevils are collected into a tray below. Like many other insects, they are also attracted to the colour yellow and can be collected on yellow sticky cards. Visual surveys for damaged buds with severed stems can also be useful when searching for strawberry blossom weevil. In collaboration with Agriculture and Agri-Food Canada’s Geomatics Team we have developed a Story Map for Strawberry Blossom Weevil to summarize our survey efforts thus far.
Pea leaf weevils may be prowling legume crops, but ground beetles and rove beetles are on the hunt as well. This Insect of the Week features two large groups of insects: ground beetles (Carabid beetles) and rove beetles (Staphylinid beetles). Many of species of ground beetles and some rove beetles are generalist predators, like ants, centipedes and spiders. These arthropods are not picky when it comes to choosing a meal and they often target pests in crop fields.
From left to right, a Carabid beetle (about 2 cm long), a Carrion beetle (about 2 cm long) and a Staphylinid beetle (less than 1 cm long). Photo credit: Jonathon Williams, AAFC-Saskatoon.
Based on research conducted in western Canada, at least two species of ground beetle have pea leaf weevil on the menu. First, a small beetle called Bembidion quadrimaculatum can feast on pea leaf weevil eggs.
Small bodied (2-3 mm long) Bembidion quadrimaculatum ground beetles can eat pea leaf weevil eggs. Photo credit: Shelby Dufton, AAFC-Beaverlodge Research Farm
A larger beetle called Pterostichus melanariuswill catch and eat adult pea leaf weevils. Other pests that different ground beetle species may eat include cutworms, aphids, wheat midge, cabbage root maggots, slugs, and many others!
A pinned Pterostichus melanarius specimen. These ground beetles eat larger prey, including adult pea leaf weevils. Photo credit: Shelby Dufton, AAFC-Beaverlodge Research FarmA ground beetle (likely from the genus Pterostichus) next to a finger for scale. Photo credit: A. Harpe, AAFC-Beaverlodge Research Farm
Ground beetles are characterized by long threadlike antennae, have a body that is flattened top-to-bottom, and have strong legs designed for running, large eyes, and obvious jaws (mandibles).
Rove beetles, like ground beetles, can be important predators of a number of insect pests! Some species will feed on pea leaf weevil eggs. One species of the rove beetle, Aleochara bilineata, is an important natural enemy of cabbage, seedcorn, onion and turnip maggots. Rove beetles are small, thin and have shortened fore-wings that leave most of their abdomen exposed.
A pinned Staphylinid (rove) beetle (<1cm long). Photo credit: Shelby Dufton, AAFC-Beaverlodge Research Farm
For more information on these field heroes and the other pests they help to manage, see the Field Crop and Forage Pests and their Natural Enemies in Western Canada guide. The guide has helpful information about the life cycle of these and other predators. The guide also has tips for conserving predators and parasitoids and pictures to help with identification. Please visit the PPMN Field Guide page to download a copy of the guide in French.
As crops are beginning to pop up – so is the pea leaf weevil (Sitona lineatus). Adults emerge in the spring and feed on legumes, such as field peas, faba beans, alfalfa, beans and lentils (causing characteristic “notching” or “scalloping” on the edges of leaves) before laying their eggs in field peas and faba beans. Each adult female can lay over 300 eggs in one summer! The eggs hatch in the soil near developing plants and larvae move to feed on nitrogen-fixing nodules. This results in partial or complete inhibition of nitrogen fixation by the plant, causing poor plant growth. Feeding by adults on the foliage and by larvae on the root nodules contributes to yield losses in field pea and faba bean crops.
Adult pea leaf weevil and a ‘u’-shaped notch resulting from feeding by the adult weevil. Photo credit: Jonathon Williams, AAFC-Saskatoon.
The pea leaf weevil is a slender greyish-brown beetle measuring approximately 5 mm in length. These insects can be distinguished by three light-coloured stripes extending length-wise down the thorax and the abdomen. All species of Sitona, including the pea leaf weevil, have a short or ‘broad’ snout unlike species like the cabbage seedpod weevil that have a long, curved snout. Mature larvae grow up to 3.5-5.5 mm long. The larvae are legless and c-shaped with a brown head.
An adult pea leaf weevil, missing some scales, but showing the stripes extending onto the pronotum/thorax. Photo credit: Jonathon Williams, AAFC-Saskatoon.
While you’re out scouting for cutworms, tachinids flies and ichneumonid wasps are scouting for them too! We have two Insects of the Week this week and both are parasitoids of cutworm pests. Parasitoids complete part of their lifecycle inside another organism, in this case cutworms, eventually killing them.
Adult tachinid flies are pale or dark brown in colour with long, bristly hairs covering their bodies. Females typically lay one to several eggs on a host. Upon hatching the larvae burrow into the host, develop inside, and then exit to pupate in the soil. Adult flies feed on flower nectar, honeydew from aphids, scale insects, and mealybugs. The tachinid, Athrycia cinerea (Coq.), is a parasitoid of the Bertha armyworm.
An adult tachinid fly (Tachinia algens) reared from glassy cutworm. Photo credit: Shelby Dufton, AAFC-Beaverlodge Research Farm.
Ichneumonidae adults vary in size and colouration but all have a narrow waist, a long abdomen, and long antennae. Females have long ovipositors that they use to inject eggs into their hosts, including cutworm larvae. Adults eat nectar and aphid honeydew. Ichneumonid larvae (including Banchus flavescens) are parasitoids of Lepidoptera, Coleoptera, Diptera, Hymenoptera, and some spiders.
An adult Ichneumonid parasitoid of the genus Banchus, reared from a dingy cutworm. Photo credit: Shelby Dufton, AAFC-Beaverlodge Research Farm.
For more information about these parasitoids, the other pests they control and other important crop and forage insects, see the Field Crop and Forage Pests and their Natural Enemies in Western Canada guide. The guide has helpful information about the life cycle of these and other parasitoids. The guide also has tips for conserving parasitoids and pictures to help with identification.
Growers are out seeding, and the cutworms are ready for it – the time to start scouting for cutworms is now! Scouting occurs by manually examining plant foliage and digging in the soil near damaged or missing plants – focus on transition zones between damaged and healthy plants. Even if you have not started seeding a field yet, consider checking volunteer plants for cutworms or feeding damage. General cutworm monitoring protocols can be found on the Monitoring Protocols page. Species-specific protocols can be found in the Cutworm Pests of Crops on the Canadian Prairies.
There are over 20 cutworm species that can cause economic damage to your crop, each with different feeding behaviour, preferred hosts, and lifecycle. Cutworms will feed on prairie-grown commodities including canola, mustard, wheat, barley, triticale, peas, alfalfa, clover, fescue, and timothy. Species identification is especially important! It helps growers determine how and when to scout, whether the cutworm species is found above-ground (climbing) or below-ground, recognize damage, and choose appropriate control options. The species of cutworm will also determine the time of day for monitoring and applying controls.
Action and economic thresholds exist for many of the cutworm species – please use them. Thresholds help control costs by eliminating unnecessary and non-economic spraying and reduce your impact on non-target insects. These non-target insects include the natural enemies that work in the background to control cutworm populations!
Pale western cutworm, Phil Sloderbeck, Kansas State University, Bugwood.org (cc-by-nc 3.0)
This week’s Insect of the Week is the Pale Western Cutworm. This cutworm feeds below ground, with larvae hatching in late April through early May. Young larvae tunnel through the soil, producing holes on newly emerged shoots and furled leaves. Older larvae will sever plants just below the soil surface and may pull and eat the severed shoots underground. Mature larvae are a pale greenish gray, with a yellow, black striped head.
AMANDA JORGENSEN, SHELBY DUFTON, JENNIFER OTANI, AND MEGHAN VANKOSKY*
The 2023 Insect of the Week season kicks off by featuring these small yet economically important beetles. Flea beetles have already been spotted across the prairies. Growers need to be wary of flea beetles even in the initial 7 days following seeding of their host crops, including canola. The best defense is in-field scouting from germination until the first true leaves unfurl and enlarge in size beyond the cotyledon leaf area. The adults create shot-hole damage visible on the topsides of the highly vulnerable cotyledons of canola but careful scouting also involves checking for feeding damage on the undersides of cotyledons and tiny canola stems where they also can feed.
Crucifer Beetle on Canola Leaf — photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org
Several species of flea beetles are present across the Canadian prairies and not all are considered pests. Historically, crucifer (Phyllotreta crucifer), striped (Phyllotreta striolata), and hops (Psylliodes punctulata) flea beetle species have caused damage in canola. Over the past decade, the bluish-black crucifer and black-with-yellow-lined striped flea beetles have proven to be consistent economic pests in canola grown across the Canadian prairies.
Striped and crucifer flea beetles feed on canola, mustard and related cruciferous plants and weeds. Canola is highly susceptible to feeding damage at the cotyledon stage – damage appears as ‘shot-holes’ in cotyledon leaves. Flea beetles also feed on stems and very young seedlings may wilt or break off under windy or damp conditions. New generation adults feed on maturing pods late in the summer. Remember, the Action Threshold for flea beetles on canola is when 25% of cotyledon leaf area is consumed.
*Information here was compiled from past PPMN Insect of the Week feature articles about flea beetles.
Key links for more information and to aid in field scouting include:
The rusty grain beetle (Cryptolestes ferrugineus) is the most common and serious pest of stored grain on farms and in elevators across the Canadian prairies. It makes up about 95 % of all grain insects detected by the Canadian Grain Commission in grain elevators across the country. Its very small size (1.5–2.5 mm long) allows it to easily crawl between grain kernels and quickly spread throughout stored grain. Its high fertility (up to 423 eggs per female) and fast development (about one generation per month) can result in serious losses if the grain is kept above 20 °C, or if it is kept too moist for too long, or if there is a hot spot or spoiled grain somewhere in the grain bin because this species thrives in spoiled grain. Additionally, the Canadian Grain Act prohibits the receipt and marketing of infested grain (i.e., grain containing any injurious, noxious or troublesome insect or animal pests). Elevators cannot accept grain if they detect this insect in it.
Rusty Grain Beetle on a kernel of wheat. Photo : Vincent Hervet, AAFC
The rusty grain beetle’s most favoured foods are: wheat, rye, corn, barley, and millet. It can also develop on a wide range of fungus species and moldy substrates. Interestingly, this beetle cannot penetrate undamaged seeds, so it requires a seed to be either spoiled, broken or cracked (a microscopic crack will suffice) in order to feed on it. Physical damage to grain is typically caused by harvesting and handling. The rusty grain beetle cannot develop below 20 °C so grain stored in dry conditions and maintained below 20 °C will be safe from infestation from this species. Keeping grain below 18 °C will ensure that it is safe from other insect species as well.
Effective ways to eliminate or reduce the risk of infestations include: • Thoroughly cleaning and sanitizing bins between uses; • Cleaning up grain residue from the surroundings to prevent the multiplication of grain insects near grain storage areas (spillages on the ground, residues left in combines or augers, etc.); • Ensuring bins are sealed tight to prevent moisture or snow from entering; • Reducing the temperature and moisture content of stored grain to safe levels as soon as possible after harvest (using these helpful Safe Storage Charts). • Also access the Canadian Grain Commission’s information on Grain Quality.
To learn more about current storage practices, storage issues, and to understand the main insect issues in stored grains across the Canadian prairies, Dr. Vincent Hervet with Agriculture and Agri-Food Canada (vincent.hervet@agr.gc.ca) is currently surveying insects in farm grain bins across the Prairie Provinces of Canada. Volunteer growers in Alberta, Saskatchewan, and Manitoba are needed to participate in this survey so we can better understand issues in farm-stored grain and how to address them.
HOW YOU CAN HELP: If you wish to participate in this survey, or if you wish to have more details about the survey, please contact Dr. Vincent Hervet (vincent.hervet@agr.gc.ca; 204-915-6918).
The foreign grain beetle (Ahasverus advena) is one of the most commonly encountered insect species in farm-stored grain in Canada. Because it often is found in stored grain, it was thought to be a grain pest, but research has shown that the foreign grain beetle is instead chiefly a mould feeder. Its presence in stored grain tells much about the state of the grain.
Because it feeds on mould, the presence of foreign grain beetles in a grain bin is a telltale sign that grain is likely going out of condition somewhere in the bin. For example, if the grain hasn’t been appropriately aerated it could be that a hot spot is forming in the centre or top of the pile, or, if snow has blown into the bin, the mouldy grain may be restricted to the top of the pile. In many instances, when we encounter foreign grain beetles we cannot readily see mouldy grain, but measuring the grain temperature and moisture content at the very centre of the top of the pile (top of the cone) should show that the condition of the grain is beyond that recommended for safe storage (see link below text) and that grain quality has likely started to deteriorate.
Foreign Grain Beetle on a kernel of wheat. Photo: Vincent Hervet, AAFC
To learn more about current storage practices, storage issues, and to understand the main insect issues in stored grains across the Canadian prairies, Dr. Vincent Hervet with Agriculture and Agri-Food Canada (vincent.hervet@agr.gc.ca) is currently surveying insects in farm grain bins across the Prairie Provinces of Canada. Preliminary results collected over the last two years in Manitoba, predominantly from stored wheat, showed grain insects were present in most bins. To our surprise, most of the insects collected were chiefly mould feeders (61 % of all insects collected in 2020 were mould feeders and 99 % of all insects collected in 2021 were mould feeders), and these mould feeders were present in 72 % of the bins sampled. The most commonly collected insect species was by far the foreign grain beetle.
Different reasons can explain these results, such as precipitations during harvest or weather conditions that did not allow for quick drying and cooling of the grain after harvest, but there may also be a lack of awareness of best storage management techniques. Therefore, we need to continue this research over the next few years to obtain meaningful data. To this end, volunteer growers in Alberta, Saskatchewan, and Manitoba are sought to participate in this survey so we can better understand issues in farm-stored grain and how to address them.
HOW YOU CAN HELP: If you wish to participate in this survey, or if you wish to have more details about the survey, please contact Dr. Vincent Hervet (vincent.hervet@agr.gc.ca; 204-915-6918).
Access these valuable resources provided by the Canadian Grain Commission: • Review or bookmark these Safe Storage Charts. • Find more information on the Management of Stored Grain.
With the 2022 growing season well underway, we decided to feature an insect that is becoming a growing problem on the Canadian Prairies: Spotted Wing Drosophila (SWD), Drosophila suzukii.
This invasive insect is thought to have originated in southeast Asia. The first record of SWD is from Japan in 1916. SWD is now established in small and stone fruit production areas throughout North America. SWD has been reported in British Columbia since 2009, and was first reported in Alberta in 2010. Occurrence in Alberta, and low levels in southern Manitoba in 2019 suggested that SK infestations were likely imminent. Monitoring for this pest conducted by the Saskatchewan Ministry of Agriculture began in 2019. Populations were detected throughout the province that year, spurring continued monitoring. Data from 2021 and 2022 indicate continued widespread distribution throughout the province. Early season detection of significant numbers suggests overwintering populations on the prairies.
SWD is an economic pest of many soft fruits, including raspberries, strawberries, cherries, blueberries and plums. Saskatoon berry has been documented as a host. Haskap is also considered to be susceptible but may escape major damage, as SWD populations typically do not increase until after harvest. However, Ontario haskap growers have seen economic losses when a mild winter is coupled with factors that lead to delayed ripening. SWD adults are 3-4 mm, yellow-brown with red eyes. Males have a conspicuous spot on the leading edge of each wing (Figure 1).
Figure 1. Spotted Wing Drosophila, male. Photo Credit: Encyclopedia of Life; Martin Cooper; University of Nebraska-Lincoln Dept. of Entomology
Females lack the spots but have a characteristic large, serrated ovipositor (Figure 2).
Figure 2. Spotted Wing Drosophila, female. Photo Credit: Encyclopedia of Life; Martin Cooper, University of Nebraska-Lincoln Dept. of Entomology
SWD overwinter as adults. These become active in the spring, mate and seek egg-laying sites. Female SWD lay as many as 16 eggs per day for up to two months. An average of 384 eggs are produced by each female. With their serrated ovipositor, female SWD deposit eggs under the skin of healthy, ripening fruit. Oviposition sites look like pin-holes in the skin (Figure 3). These can also serve as avenues of entry to pathogens like brown rot and botrytis.
Figure 3: SWD-damaged cherry showing oviposition scars. Photo Credit: Martin Hauser, California Department of Food and Agriculture
Several larvae can occur per fruit (Figure 4). Larval feeding causes fruit to become prematurely soft and unmarketable. Larvae mature in 3-13 days and pupate most commonly in the fruit. The pupal stage lasts another 3-15 days. Multiple generations per year are common.
Although SWD adults can be moved around by winds, movement of contaminated plant material is the major route for initial dispersal. Current management includes culling and destruction of soft fruit and the application of insecticides to limit populations. There are several products registered to control SWD. These can be found here: http://pr-rp.hc-sc.gc.ca/ls-re/index-eng.php. Use the search term ‘spotted wing drosophila’. Product updates occur periodically so check this site regularly.
Western bean cutworm (Striacosta albicosta) is a native North American insect that, at high levels, can be a pest of corn and dry beans. However, the way they feed is different than some of the other cutworms many may be familiar with. Western bean cutworm feeds on the reproductive parts of plants (corn tassel, silks, and kernels, or dry bean pods and seeds). This can result in yield loss, and spread ear mold. In Ontario, injury by western bean cutworm has been shown to increase mycotoxin production in grain corn.
Range Expansion: The historical geographic range of the western bean cutworm covered the western Great Plains states including Colorado, Nebraska, and Wyoming but, over the past two decades, its distribution has been more easterly rather than north to the prairies. A report from the 1950s of western bean cutworm in Alberta has instead been confirmed as a misidentification of another species. Currently, it has not been detected in the Canadian prairie provinces. Since 1999, the geographic range of the western bean cutworm has rapidly expanded eastward across the U.S. Corn Belt and eastern Canada. Western bean cutworm adults have been collected in 22 additional states and provinces since 1999, spreading from western Iowa to the east coast of the United States and Canada. It was first found in Canada in Ontario in 2008. Keep an eye open for this insect when scouting for crop pests in corn or dry beans this summer.
Figure 1. Detailed expansion of western bean cutworm distribution into the eastern Corn Belt between 2000 and 2017. From: Smith et al. 2019. Journal of Integrated Pest Management. Volume 10, Issue 1, pg. 1-19.
Appearance and monitoring tips: Larvae: • There are six stages (instars) of the larvae, and appearances vary. • Older larvae are a light tan colour, with an orange head. The pronotum (the shield-like structure just behind the head) has two broad dark brown stripes. • You may find young larvae on the silks of corn. Older larvae may be on the ears of corn, but you may have to peel back the husks to find them (Fig. 2).
Figure 2. Western bean cutworm feeding on corn. Photo: Jocelyn Smith, University of Guelph.
Adults: • Each forewing has a white or tan band running along the edge or margin of the wing (Fig. 3). Inside this band are 2 distinctive markings: a brown circle and a brown kidney bean shape, both surrounded by a tan border. Note – Other moths across the Canadian prairies, such as redbacked cutworm, have similar markings.
Figure 3. Western bean cutworm adult. Photo: Jocelyn Smith, University of Guelph.
Please help – When monitoring in the Canadian prairies, adults or larvae suspected to be western bean cutworm can be directed to your provincial entomologist for species verification. New and confirmed sightings of this species are important and will help mobilize research and pest management strategies.
Additional information on western bean cutworm can be found in the publication “Western Bean Cutworm” by the Canadian Corn Pest Coalition: https://cornpest.ca/corn-pests/western-bean-cutworm/
Did you know? Bt corn with the Vip3A protein effectively controls western bean cutworm, but some of the Bt corn products for European corn borer will not.
Reference: Ecology and Management of the Western Bean Cutworm (Lepidoptera: Noctuidae) in Corn and Dry Beans—Revision With Focus on the Great Lakes Region. 2019. J. L. Smith, C. D. Difonzo, T. S. Baute, A. P. Michel, and C. H. Krupke, Journal of Integrated Pest Management, Volume 10, Issue 1: 1-19.
Despite its common name, the European corn borer (Ostrinia nubilalis) feeds on many crop and non-crop plants including beans, potato, quinoa, millet, hemp, wheat, many vegetables and some flowers. European corn borer is occasionally an economic pest of crops such as corn and potatoes in Manitoba, where there is one generation per year. In parts of Ontario and eastern Canada, there are univoltine (one generation per year) and bivoltine (two generations per year) strains. How prevalent and damaging European corn borer is to many of its host crops is still not clear.
European Corn Borer larva in millet. Photo credit: John Gavloski, Manitoba Agriculture
European corn borer has traditionally been monitored in corn fields, and more recently in potato fields. However, a new harmonized protocol can be used to monitor for European corn borer in multiple crops. Anyone participating in insect monitoring on any potential host crop can access the harmonized protocol online or using the Survey123 app.
The protocol can be used to report the presence of European corn borer eggs, larvae, and crop damage. Anyone monitoring populations or encountering noticeable levels of European corn borer or their injury to any crop is highly encouraged to add this data. For more information about the harmonized protocol and to submit monitoring data, please click here to access all needed links. Information collected from across Canada will be used to better understand the distribution, feeding habits, and abundance of this pest.
European Corn Borer egg masses. Photo credit: John Gavloski, Manitoba Agriculture
Access these resources to find more information: • Review the European corn borer page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) also accessible as a free downloadable PDF in either English or French on our new Field Guides page. • Review the Manitoba Agriculture fact sheet for the European corn borer. • Review the Ontario Ministry of Agriculture, Food, and Rural Affairs fact sheet for European corn borer.
Thrips (used for both singular and plural) are members of the Order Thysanoptera. Even more confusing, there is also a genus of thrips named Thrips. That is, all Thrips are thrips but not all thrips are Thrips!
Thrips are characterized by small size (the largest species is only 2 mm as adults; the smallest is 0.6 mm), long slender bodies, and fringed wings (winged and wingless adults exist in some species). Males are smaller than females.
Figure 1: Adult thrips on barley leaf showing off fringed wings neatly folded over its abdomen. Photo: Sheila Elder, Saskatchewan, Canada
Adult thrips are generally relatively weak flyers and employ a‘clap and fling’ technique. The animal claps the leading edges of its wings together at the end of the upstroke then rotates the wings around the trailing edges, flinging them apart. Many small insects use this technique to promote air circulation and generate lift quickly. Pigeons also use this technique for their noisy flight initiations. For small insects, the viscosity of the air has a much greater effect than on larger animals. Fringed wings reduce drag associated with this effect.
There are about 6,000 species of thrips worldwide with 147 described species in two suborders in Canada, including 28 non-natives. Recent molecular work indicates that there may be as many as 255 additional as-yet-undescribed species in Canada. The most common and broadly distributed family is the Thripidae, followed by the Phlaeothripidae and Aeolothripidae. Other families are far less represented.
Although some species are important for pollination and a few are predators of other small insects, some are pests in crops. They have unique, asymmetrical mouthparts characterized by a greatly reduced right mandible. Their feeding is described as ‘rasping-sucking’: they scrape the surface of plant tissue and ingest fluid flowing from the wound. When feeding on actively growing plant tissue, growth reductions and distorted growth may be observed and yield loss can occur. When they feed on more mature tissue, silver leaf scars can occur that reduce the quality and marketability of some crops. Thrips are also important vectors of topsoviruses.
One suborder of thrips lays very small eggs (0.08 mm to 0.2 mm) singly in slits in plant tissue; the other lays eggs on plant surfaces. Eggs hatch into nymphs: juveniles resemble adults but are not sexually mature and have no wings. There are two juvenile feeding stages, followed by two non-feeding stages: pre-pupa and pupa.
The barley thrips, Limothrips denticornis, was first reported in North America in 1923 in New York. In its native Europe and Asia, it can be found on a wide variety of grass species but is a minor pest and only on rye. In North America, it is generally more important on barley, though it can be found on winter wheat, durum, winter rye, corn, and triticale. Adults are small (1.1 mm to 1.8 mm), elongate, and dark brown to black. These thrips lay eggs on upper leaf sheaths and each female can produce 100 eggs. Juveniles are smaller and lighter coloured. Barley thrips overwinter as adults and move to winter grasses in the spring. They are somewhat stronger flyers than many thrips species, but are still limited by their size. In Northern Europe, cereal thrips, including L. denticornis, have been reported to appearin large numbers ahead of thunderstorms. This may be associated with the warm conditions that precede these events, but it has also been suggested that they are sensitive to the electrical fields associated with storms.
Another cereal thrips, Limothrips cerealium, has also been reported in Canadian small grains cereals and was reported in 1928 to be responsible for 10 per cent losses in oats in Canada.
Thrips feeding on cereals can result in tissues appearing bleached. When numbers are high and feeding is intense, kernels can be shriveled. Severe flag leaf feeding can result in kernels filling improperly and reduced kernel weight.
Figure 2: Thrips nestled at the base of leaf. Photo: Sheila Elder, Saskatchewan, Canada
Scouting for barley thrips should be done from first sign of flag leaf until the head is completely emerged from the boot. Barley thrips can be found on stems but are more commonly under the top two leaf sheaths. Because thrips are relatively weak flyers, there may be greater concentrations in protected field edges. Greatest damage has been reported in dryland cropping areas after prolonged drought.
Economic thresholds:
Threshold (thrips/stem) = (Cost of control per acre / expected $ value per bushel) / 0.4
.Sample at least 50 stems from different parts of the field. One adult thrips per stem can cause a loss of 0.4 bushels per acre. This usually translates to an action threshold for barley and oats of 7 – 8 thrips/stem prior to heademergence but greater precision can be achieved by using the formula. The action threshold is the number of insects detected that can cause enough damage to justify the expense and effort of applying control. Numbers lower than this do not warrant control. Only apply control prior to the completion of heading.
Thresholds for cereal thrips have been determined for barley and oats but effects on other cereals crops in North America are less well understood. Work in Europe indicated comparable damage per thrips in rye, triticale, and winter barley. Recent reports of barley thrips in durum also suggest a risk of damaging effects, but these are not as well understood. A report from Germany indicated that, despite some relatively high thrips numbers, there was no correlation between barley thrips and damage. However, there is also evidence from Europe of the importance of long crop rotation to thrips damage control in wheat.
Even damaging insects can be beautiful! In fact, showy invasive species often are detected earlier compared to smaller, less colourful, or more cryptic or camouflaged species. The European skipper (Hesperiidae: Thymelicus lineola) is a good example of a bright orange butterfly large enough to easily spot on the wing that is diurnal (Fig. 1, 6). Unfortunately, the predominantly green larvae are defoliators capable of causing economic levels of damage in timothy but they also feed on a number of other grasses and winter wheat.
Figure 1. European skipper (Thymelicus lineola) adults on timothy seed heads. Photo: S. Dufton, AAFC-Beaverlodge.
There is one generation per year of European skipper but butterfly oviposition or egg laying largely dictates where damage occurs the following summer. Early in July, butterflies feed on nectar, mate, and lay eggs. Females lay vertical rows or “strings” of groups of ~30 eggs on the inside of grass leaf sheaths, seed heads or on the stem of a host plant. By late July, larvae develop within the eggs yet they remain safely enclosed to overwinter inside the egg shell. Early in May, the overwintered larvae emerge from the shell, crawling up growing grass blades to feed. Five larval instar stages cause damage by defoliation of the upper leaves of timothy. Adult wingspans range from 19-26 mm but they have bright brassy orange wings with narrow black borders and hindwing undersides that are pale orange and greyish. The typical flight season extends from early June to mid-July but will vary regionally with southern parts of the Canadian prairies starting earlier than more northern regions.
Larvae are leaf-tyers that spin and attach silk ties across the outer edges of leaves to pull them together (Figs. 2-5). The silk ties hold the leaf in a tight furl enclosing the larva within a leafy tube then it moves up and down the tube to feed. The tying behavior and camouflaged green body (marked longitudinally with two white lines) make larvae hard to locate when scouting. Even larger larvae with their brown head capsules are surprisingly difficult to locate because the larva will lie lengthwise, along the base of the leaf fold yet remain very still until touched. When high densities of European skipper larvae are present, leaf tying goes out the window and larvae feed in more exposed areas, often amidst rapidly disappearing foliage.
Figure 2. Early instar larva feeding along edge of timothy leaf. Photo: A. Jorgensen, AAFC-Beaverlodge.
Figure 3. Larva resting in fold of timothy leaf formed by silken tie. Photo: K. Pivnick, AAFC-Saskatoon.
Figure 4. Larval feeding damage and silken ties on timothy leaf. Photo: K. Pivnick, AAFC-Saskatoon.
European skipper (Thymelicus lineola) was introduced to North America decades ago and has moved west and north in its distribution across western Canada even though its area of origin is recognized as Eurasia and northwestern Africa. The initial report of European skipper in Canada is from 1910 and cites it being imported on contaminated timothy seed near London, Ontario. Eggs can be transferred in both hay and seed as seed cleaning will not remove all eggs.
Distribution records for T. lineola can be reviewed on the Butterflies of North America website. In western Canada, T. lineola established in parts of Saskatchewan by 2006. In 2008, butterflies were collected near Valleyview, Alberta (Otani, pers.comm.), and in 2015 larvae were observed feeding in the flag leaves of winter wheat near Mayerthorpe, Alberta (2015 Meers, pers. comm.). Specimens confirmed as T. lineola were collected in 2016 near Valleyview, Donnelly, and High Prairie, Alberta (2017 Otani and Schmidt, pers. comm.) with additional specimens confirmed from Baldonnel and Clayhurst, British Columbia in 2021 (2021 Otani and Schmidt, pers. comm.).
Cultural control strategies for European skipper include separating timothy from nectar sources to avoid attracting adults which will mate then oviposit in the same field. Another strategy is the removal of cut grass or bales. In terms of chemical control, an action threshold of six or more larvae per 30 cm x 30 cm area is recommended to mitigate losses but emphasis should be placed on scouting and managing early instar larvae. If the need arises, chemical control in timothy involves using a higher water volume (e.g., 300 L H2O/ha) to adequately cover the thicker canopy.
Figure 5. In situ camouflaged larvae and feeding damage in timothy. Photo: S. Barkley.
Interesting fact: In Europe, Thymelicus lineola is commonly referred to as the Essex Skipper.
The Canadian Food Inspection Agency (CFIA) and entomologists are on the lookout for Spotted Lanternfly (Lycorma delicatula), a new invasive species in the United States that could move north into Canada. This very distinctive bug has tan-coloured forewings with black spots and can be quite large as adults (about 2.5 cm long by 1 cm wide). The underwing of the adults has bright red or pink highlights.
Spotted Lanternfly. Photo credit: Dr. Bryan Brunet, AAFC Ottawa
Spotted Lanternfly is native to Asia but was detected in Pennsylvania, United States of America, in 2014. Since then, it has been found in many states in the northeast of the United States, including Connecticut, Delaware, Maryland, New Jersey, New York, Ohio, Virginia, and West Virginia. It can disperse short distances as an adult or nymph by walking or flying, but eggs can be moved long distances by humans, especially if they are laid on vehicles, packing materials, or other items that are moved by humans. It is very important to inspect vehicles for egg masses if you are traveling back to Canada from areas where spotted lanternfly is established.
Spotted Lanternfly Egg Mass. Photo credit: Holly Raguza, Pennsylvania Department of Agriculture, Bugwood.org
Adults and nymphs of the spotted lanternfly feed on their host plants by sucking sap from leaves and stems. Their preferred host plant is tree-of-heaven, a plant introduced to North America. However, spotted lanternfly also feeds on grapes, apples, plums, cherries, peaches, nectarines, apricots, oak, walnut, and poplar trees. Thus, this insect could be a significant threat to the orchard and forestry industries in Canada.
Spotted lanternfly is on the CFIA regulated pest list, thus, it is our responsibility to report sightings. Early detection of this invasive insect is the best way to eradicate it and prevent it from becoming established in Canada. If you think you have seen or found a spotted lanternfly, report it to the CFIA Canadian Food Inspection Agency / Agence canadienne d’inspection des aliments. Refer to this PDF copy of an expanded description of this invasive species.
You can also upload sightings to iNaturalist.ca and tag @cfia-acia in the comment section of your observation to reach the CFIA experts.
This week’s insect, the strawberry blossom weevil (Anthonomus rubi) is a recent invader to British Columbia. It is native to Europe, Asia, and parts of North Africa. As its name implies it is a serious pest of strawberries, however, it does have a much wider host range including many plants in the family Rosaceae – raspberries, blackberries, and roses to name a few.
It was first found in Abbotsford, British Columbia (BC) in 2019 on raspberries and has since been found to be established throughout the Fraser Valley of BC on cultivated and wild host plants. This is the first report of strawberry blossom weevil in North America. Due to the presence of strawberry blossom weevil in BC, the United States Department of Agriculture Animal and Plant Health Inspection Service (APHIS) amended entry requirements for Fragaria, Rubus, and Rosa plants. The USA now requires a phytosanitary certificate to move these plants from Canada into the USA (Federal Order DA-2021-25).
The strawberry blossom weevil lays its eggs in closed buds and clips the stem just below to prevent further bud development.
The egg hatches and the weevil larva develops inside of the damaged bud. Once mature, an adult weevil chews a hole in the bud from which it emerges. It completes a single generation per year. In Europe, bud losses associated with strawberry blossom weevil damage range from 5 to 90% and have led to yield losses over 60%. The strawberry blossom weevil can be confused with the strawberry clipper weevil (Anthonomus signatus) in Canada due to its similar biology and crop damage.
Although there is a historical record of strawberry clipper weevil being in BC, it is primarily a pest in berry crops in eastern Canada and has not been detected during our surveys in 2020-2022 in southwest BC. Adult strawberry blossom weevils are small (2.5-3.0 mm), black, with a small white patch of scales on the scutellum (back), and a long slender rostrum (snout). Larvae, found within damaged buds are c-shaped, with a yellowish-brown head capsule and cream coloured body that grows to 2.5 to 3 mm.
Adult weevils naturally drop when disturbed so they can be detected using beat sampling (tapping) in plants. They are also detectable using yellow sticky cards. Visual surveys for damaged buds with severed stems can also be useful when searching for strawberry blossom weevil.
Although this pest has not been detected to date on the Prairies, a nationwide survey is underway this summer to delineate the distribution of this pest in Canada. In collaboration with Agriculture and Agri-Food Canada, a Story Map has been created to provide an easily digestible summary of the survey underway using pictures, text, and interactive maps all accessible here. We are looking for community-based records of strawberry blossom weevil so, if you would like to get involved, please submit pictures of any suspected strawberry blossom weevil to our iNaturalist project (Anthonomus rubi in North America · iNaturalist).
This week we look at a small sap-feeding insect with a high economic threshold, and how counting a few beneficial insects helps make informed economical management decisions.
Soybean aphid (Aphis glycines) was first found in North America in 2000. They are specific, feeding and functioning as a potential pest of ONLY soybeans (Fig. 1). Like some other aphids, soybean aphids overwinter on an alternate plant host completely different from their main summer soybean host; they overwinter as eggs only on buckthorn (Rhamnus sp.). It is not known if soybean aphids overwinter well in the Canadian prairies. Every spring, populations of soybean aphid may be highly dependent on what moves in, and when. There have been years when this newly established insect was at economic levels, but high populations are erratic and do not occur every year.
Figure. 1 Soybean aphids on underside of soybean leaf. Photo: J. Gavloski
Appearance and monitoring tips for soybean aphids (Fig. 2): • Small, light yellow, with black cornicles (tailpipes). • Winged adults have black heads and thorax. • A hand-lens may be helpful for verification.
Figure 2. Dorsal view of mature soybean aphid. Photo: J. Gavloski
Sample weekly, even daily, after bloom. Check the undersides of leaves to look for aphids. Ants on plants may hint that aphids are present (some ant species like feeding on aphid honeydew). To avoid bias and inaccurate estimates of pest populations, RANDOMLY select soybean plants to assess then count and note soybean aphid densities.
If aphid levels are high, numbering in the hundreds, exact counts are not possible and likely impractical. Instead, practice visually estimating densities (Fig. 3). Photo keys are available to help. Don’t count the white shed cuticles you may see on plants with many aphids.
Figure 3. Examples of different soybean aphid densities. Photo: J. Gavloski
An app called Aphid Advisor, factors several natural enemies into the management decision and recommends looking for several natural enemies, such as lady beetles (Fig. 4), lacewings, hover fly larvae (Fig. 5), minute pirate bugs, parasitized aphids, etc. Information on Aphid Advisor is available at: http://www.aphidapp.com
The action threshold (density where action is recommended to mitigate damaging densities associated with economic loss) is an average of 250 aphids per plant applied from onset of bloom to early stages of seed development and typically involves rapidly increasing aphid populations. If using Aphid Advisor, a dynamic action threshold, which includes the impact of natural enemies, will be calculated.
If control of soybean aphids is necessary, selective insecticides that kill aphids but are harmless to their natural enemies are now available. See your provincial Guide to Crop Protection or contact your local provincial entomologist for more details.
Figure 4. Lady beetle larva foraging amongst soybean aphids. Photo: J. Gavloski
Figure 5. Larvae of two different species of hover fly (Syrphidae) foraging amongst soybean aphids. Photo: J. Gavloski
Additional information on soybean aphids can be found in the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management: AAFC-Field-Guide (2018) as both ENGLISH and FRENCH resources that are freely downloadable and searchable.
Did you know? Pinkish, white, or tan and fuzzy soybean aphids are infected with a fungus! Fungal pathogens can reduce aphid numbers in warm and humid conditions.
References: Ragsdale, D.W., B. P. McCornack, R. C. Venette, B. D. Potter, I. V. MacRae, E. W. Hodgson, M. E. O’Neal, K. D. Johnson, R. J. O’Neil, C. D. DiFonzo, T. E. Hunt, P. A. Glogoza, and E. M. Cullen. 2007. Economic Threshold for Soybean Aphid (Hemiptera: Aphididae). Journal of Economic Entomology. Vol. 100: 1258-1267. https://doi.org/10.1093/jee/100.4.1258
Hallett, R.H., C.A. Bahlai, Y. Xue and A.W. Schaafsma. 2014. Incorporating Natural Enemy Units into a Dynamic Action Threshold for the Soybean Aphid, Aphis glycines (Homoptera: Aphididae). Pest Management Science. Vol. 70: 879-888. https://doi.org/10.1002/ps.3674
This week wraps up our series on Prairie wireworms, and we are ending with a bit of an odd one, the flat wireworm (Aeolus mellillus).
The flat wireworm is not found in huge abundance on the Prairies, but it is worth knowing about because it’s different than the other 3 main species. First, it is quite recognizable with its dark reddish-brown head and stripe below its head.
A. mellillus (arrow)
Second, if you ever get one of these in the palm of your hand, it is very active, it will be hard to hold on to it before it crawls away. This activity may be because the flat wireworm is also a predacious species, in fact it might eat other wireworms! But it also eats plants, and the literature says it cuts plants rather than the shredding type of feeding shown by other species. The flat wireworm can grow fast to its mature size of 15 mm. Unlike other wireworm species, Aeolus mellillus has a short 1-2 year life cycle and can pupate anytime between spring and late summer. This species also does not need to mate to reproduce – as far as we know, Canadian populations of A. mellillus are all females!
AAFC has recently released a new field guide on Prairie pest wireworms. It has information on biology, monitoring and management and research on wireworms on the Prairies. Preview pages extracted from the guide highlighting Aeolus mellillus by clicking here.
Free digital copies in both official languages can be downloaded at these links.
Continuing our series on Prairie wireworms, this week we highlight the sugarbeet wireworm, Limonius californicus.
This species is less abundant than Hypnoidus bicolor or the Prairie grain wireworm (Selatosomus aeripennisdestructor), but some fields have a major problem with this species. Limonius californicus wireworms are 17-22 mm long at maturity and can be aggressive feeders. The literature reports it is more likely to be found in irrigated fields.
The life cycle of L. californicus on the Prairies is not well known. Our current information is based on lab studies in California in the 1940s, where larvae lived for 2-5 years before undergoing metamorphosis into adult click beetles.
Wireworm size varies within a species depending on age. Photo: W. van Herk, AAFC-Agassiz
AAFC has recently released a new field guide on Prairie pest wireworms. It has information on biology, monitoring and management, and research on wireworms on the Prairies. Preview pages extracted from the guide highlighting Limonius californicus by clicking here.
Free digital copies in both official languages can be downloaded at these links:
Free hard copies are also available while supplies last. Email Haley Catton at haley.catton@agr.gc.ca to request your copy.
Did you know?
– A new pheromone has recently been discovered by researchers at Simon Fraser University AAFC that attracts male beetles. This pheromone will help monitoring efforts.
References:
Gries R, Alamsetti SK, van Herk WG, Catton HA, Meers S, Lemke E, Gries G (2021) Limoniic acid – major sex pheromone component of the click beetles Limonius canus and L. californicus. Journal of Chemical Ecology 41:123-133. https://doi.org/10.1007/s10886-020-01241-y
Van Herk, W. G., Labun, T. J., & Vernon, R. S. (2019). Efficacy of diamide, neonicotinoid, pyrethroid, and phenyl pyrazole insecticide seed treatments for controlling the sugar beet wireworm, Limonius californicus (Coleoptera: Elateridae), in spring wheat. Journal of the Entomological Society of British Columbia, 115, 86-100.
Continuing our series on Prairie wireworms, this week we highlight the Prairie grain wireworm, Selatosomus aeripennis destructor.
This species is native to the Prairies and is the second most abundant wireworm in Prairie crop fields, but it likely causes the most damage. This wireworm is big and beefy, it grows up to 23 mm long when mature and has a stout build. Its aggressive feeding style can destroy 10 times as many seeds as its cousin, Hypnoidus bicolor, a species that is often found together within the same fields.
Size of resident wireworms can vary with species. Selatosomus aeripennis destructor (left) and Hypnoidus bicolor (right). Photo: W. van Herk, AAFC Agassiz . Photo taken from the Pest Wireworm Guide
Interestingly, click beetles of this species rarely fly, they mostly walk to find mates and choose locations to lay eggs. A new pheromone has recently been discovered by researchers at Simon Fraser University and AAFC that can be used to attract male beetles. This pheromone will help monitoring efforts.
AAFC has recently released a new field guide on Prairie pest wireworms. It has information on biology, monitoring and management and research on wireworms on the Prairies.
Free digital copies in both official languages can be downloaded at these links.
See this week’s wireworm information in the free, downloadable guide: English ; French
Did you know?
Prairie grain wireworm has a closely-related subspecies called Puget sound wireworm (Selatosomus aeripennis aeripennis). This species looks almost identical to Prairie grain wireworm and can be a pest in the Aspen Parkland Ecoregion.
Reference:
Gries, R., van Herk, W., Alamsetti, S.K., Catton, H., Meers, S., Otani, J., Gries, G. (2022) (Z,E)-a-Farnesene – sex pheromone component of female click beetle Selatosomus aeripennis destructor (Brown) with intra- and inter-sexual communication function. Entomologia Experimentalis et Applicata. 170:344-351. https://doi.org/10.1111/eea.13142
Continuing our series on Prairie wireworms, this week we highlight Hypnoidus bicolor.
This species is the most abundant in Prairie crop fields and is a native species. Despite its abundance, it has no common name. Hypnoidus bicolor larvae are relatively small (10-12 mm long when mature) and are often found in the same fields as next week’s PPMN Insect of the Week, Prairie grain wireworm (Selatosomus aeripennis destructor, up to 23 mm long when mature).
Size of resident wireworms can vary with species. Selatosomus aeripennis destructor (left) and Hypnoidus bicolor (right). Photo: W. van Herk, AAFC-Agassiz
Although this species is abundant, it may not be as aggressive of a feeder than its cousin the Prairie grain wireworm. An interesting feature of this species is that it has different populations, some of which are all females. What we call H. bicolor today may actually be several species or subspecies based on genetic differences. We estimate that the larvae of this species live in the soil for 2-3 years but this has not been verified.
AAFC has recently released a new field guide on Prairie pest wireworms. It has information on biology, monitoring and management and research on wireworms on the Prairies. Preview the Hypnoidus bicolor pages of the new wireworm guide here.
Free digital copies in both official languages can be downloaded at these links.
Free hard copies are also available while supplies last. Email Haley Catton at haley.catton@agr.gc.ca to request your copy.
Main pest wireworm species on the Canadian Prairies: larval stages (top), adult (click beetle) stages (bottom). Photos: J. Saguez, CEROM
Did you know ?
– H. bicolor is in the same genus as the main pest species in Quebec, the abbreviated wireworm Hypnoidus abbreviatus.
Reference:
Drahun, I., Wiebe, K.F., Koloski, C.W., van Herk, W.G. and Cassone, B.J. (2021), Genetic structure and population demographics of Hypnoidus bicolor (Coleoptera: Elateridae) in the Canadian Prairies. Pest Manag Sci, 77: 2282-2291. https://doi.org/10.1002/ps.6255
Wireworms are the larvae of click beetles (Coleoptera: Elateridae). They are serious pests of many field crops across Canada, particularly cereals, pulses, root crops. Wireworms live for multiple years in the soil, eating crops from below – their underground habitat can make them difficult to detect and diagnose. Damage in cereals and pulse crops will appear as early season crop thinning or yellowing, weakened plants. Root crops may look fine aboveground but at harvest, produce will have feeding holes or disfigurations, decreasing market value.
When crop thinning is seen, post-emergence scouting by digging up plants and soil can reveal if wireworms are there. Photos: H. Catton, AAFC-Lethbridge.
There are several pest wireworm species in the Prairies and they are different than in other regions of Canada. A 2004-2019 survey of Prairie crop fields published by Wim van Herk and colleagues collected 5,704 specimens. This survey revealed that 97% of specimens belonged to 4 native species: 58% were Hypnoidus bicolor (no common name), 22% were Prairie grain wireworm (Selatosomus aeripennis destructor), 15% were sugarbeet wireworm (Limonius californicus), and 2% were flat wireworm (Aeolus mellillus). Importantly, the invasive wireworm species dominating coastal BC and the Atlantic provinces (Agriotes obscurus, Agriotes lineatus, Agriotes sputator) were NOT found in the survey. Over the next several weeks our Insect of the Week articles will highlight the main pest wireworm species on the Prairies.
Main pest wireworm species on the Canadian Prairies: larval stages (top), adult (click beetle) stages (bottom). Photos: J. Saguez, CEROM
Monitoring for wireworms can be done in different ways. Before seeding, bait traps can be placed in the soil. After crop emergence, hand digging in thinned areas of crop may reveal wireworms. Finally, monitoring for adult click beetles may be able to indicate if wireworm populations are high – this method is still in development. Unfortunately, there are no economic thresholds developed for wireworms, farmers need to judge yield loss from thin or bare patches caused by wireworms.
AAFC has recently released a new field guide on Prairie pest wireworms. It has information on biology, monitoring and management and research on wireworms on the Prairies.
Free digital copies in both official languages can be downloaded at these links.
Free hard copies are also available while supplies last. Email haley.catton@agr.gc.ca to request your copy.
Reference:
van Herk WG, Vernon RS, Labun TJ, Sevcik MH, Schwinghamer TD (2021) Distribution of pest wireworm (Coleoptera: Elateridae) species in Alberta, Saskatchewan, and Manitoba (Canada). Environmental Entomology 50:663-672. doi: 10.1093/ee/nvab006
Shot-hole feeding on seedling canola is NOT a pretty sight in newly emerging stands but growers need to be wary of flea beetles even in the initial 7 days following seeding. The best defense is in-field scouting which continues from germination until the first true leaves unfurl and enlarge in size beyond the cotyledon leaf area. Overwintered adults are highly mobile and attracted to yellow. They even orient towards kairomones released by canola and other closely related Brassicaceae.
Adults are defoliators and small in size, ranging 2-3 mm in length. Even so, the combination of high densities of flea beetles and adverse growing conditions that slow canola seedling growth and extend the vulnerable number of days plants remain seedlings. In some cases, daily in-field monitoring may be necessary to protect canola seedlings from high densities of flea beetles that move into a field en masse.
Crucifer Beetle on Canola Leaf — photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org
Several species of flea beetles are present across the Canadian prairies and not all are considered pests. Historically, crucifer (Phyllotreta crucifer), striped (Phyllotreta striolata), and hops (Psylliodes punctulata) flea beetle species have caused damage in canola. Over the past decade, the bluish-black crucifer and especially black-with-yellow-lined striped flea beetles have proven to be consistent economic pests in canola grown across the Canadian prairies.
The 2022 Insect of the Week kicks off by featuring these small yet economically important 2-3 mm long beetles. The adults create shot-hole damage visible on the topsides of the highly vulnerable cotyledons of canola but careful scouting also involves checking for feeding damage on the undersides of cotyledons and tiny stem where they also can feed.
Striped Flea Beetle–Photo: Mike Dolinski, MikeDolinski@hotmail.com
Spotted wing drosophila CC BY 2.0 Oregon State University
This invasive insect is thought to have originated in southeast Asia. The first record of spotted wing drosophila (Drosophila suzukii) is from Japan in 1916. Spotted wing drosophila is now established in small and stone fruit production areas throughout North America. These insects have been found in Saskatchewan, Alberta and southern Manitoba, but more work is needed to determine if there are established populations that cause economic damage on the prairies. Spotted wing drosophila is an economic pest of many soft fruits including raspberry, strawberry, saskatoon berry, blueberry, cherry and plum.
Larval feeding causes fruit to become prematurely soft and unmarketable. Larvae mature in 3-13 days and pupate most commonly in the fruit. This feeding also increases the risk of fungal infections in the fruit like brown rot or botrytis.
Spotted wing drosophila adults are 3-4 millimetres long, with a yellow-brown body and red eyes. Males have a conspicuous spot on the leading edge of each wing. Females lack the spots but have a characteristic large, serrated egg-laying organ (ovipositor) that allows them to pierce the skin of the fruit where they lay their eggs. Larvae are white maggots that grow up to 3 millimetres long. While the larvae are tapered on both ends and have no clearly defined head, they possess two dark “mouth hooks” at the front.
Homemade spotted wing drosophila trap CC BY 2.0 Oregon State University
Biological and monitoring information related to spotted wing drosophila in field crops can be found on our Monitoring page as well as on the Manitoba Agriculture and Resource Development website.
As the name suggest, the Japanese beetle is native to Japan but has been present in North American since 1916. While an annual trapping program in Canada has been in place since 1939, complete elimination has not been achieved. Fortunately, it has not reached the Prairies yet, but it is found in southern Ontario, Quebec, New Brunswick, Prince Edward Island and Nova Scotia. It has been detected in Vancouver, British Columbia and the CFIA is leading a coordinated eradication program and has implemented efforts to prevent the pest’s spread outside Vancouver. The rest of British Columbia is still considered free of Japanese Beetle. In the USA, eastern states are considered generally infested (from Minnesota south to Arkansas and across to the Atlantic Coast, excluding Mississippi [partial infestation], and Florida and Louisiana [no infestation]); central states are partially infested (from North Dakota south to Texas); and western states (including Alaska and Hawaii) have no infestations (USDA Japanese Beetle FAQ). Quarantine and phytosanitary regulations are in force to limit movement of infested materials from infested states into or through non-infested states to protect the agriculture sector.
Potential host plants on the Prairies include corn and soybean, but the Japanese beetle also targets fruit crops like peach, apple, apricot, cherry and plum, as well as berries like blueberry, raspberry. Damage from adult Japanese beetles includes leaves that have been chewed down to the vein. Damaged leaves turn brown and drop, leaving plants vulnerable to disease and limiting overall growth. Larvae feed on roots, causing additional stunting in addition to potential wilting and sometimes death.
Adults are almost 10 millimetres long and oval. Their abdomen, thorax and head are metallic green with metallic copper-brown wing coverings and white hair along the abdomen. Larvae grow to 25 millimetres and are C-shaped white grubs with a yellowish-brown head. A V-shaped spine arrangement can be seen on the last body segment.
Japanese beetle larval development (David Cappaert — Michigan State University CC-BY 3.0)
Biological and monitoring information related to Japanese beetles in field crops can be found on our Monitoring page. For more information, visit the Japanese beetle page on the Canadian Food Inspection Agency website.
With a common name that cites the devastation these insects brought upon crops during an 1848 outbreak in the Great Salt Lake Basin, Mormon crickets have equal potential to do damage on the Canadian Prairies. Like other grasshopper species, mormon crickets will consume various crops, including wheat, barley, alfalfa and sweet clover, in addition to other forages and garden vegetables. These crickets will also eat other insects, including smaller mormon crickets.
Droughts drive mormon cricket outbreaks, at which time these insects will have a greater economic impact on crops. Migrating swarms will consume all parts of their plant host, ravaging crops and reducing their marketable yields. In addition to this, baled alfalfa containing crickets is unpalatable to livestock, reducing its viability as a feed source.
Adults are 40-50 mm long with stout bodies. Their colour depends on how dense the population is: swarming mormon crickets can be black, brown, or red, and individual insects can be purple or green. Both the abdomen and the “shield” (pronotum) behind the crickets’ head may be striped. The females’ have a long egg-laying organ (ovipositor) and both sexes have antennae longer than their bodies. Mature nymphs resemble adults in colour and appearance but are somewhat smaller and females lack an ovipositor.
Adapted to all ecoregions in the Canadian grasslands, the migratory grasshopper is a versatile insect demonstrating variable colouration and a range of adult sizes. While a common pest in the Prairie region, the migratory grasshopper has a range that extends southward into Florida. These insects will consume almost all crops, including (but not limited to) forage legumes and grasses, pulses, oilseeds, cereals, and vegetables. Despite their name, migratory grasshoppers overwinter in the Prairie region.
As a mixed feeder, the migratory grasshopper thrives in many agricultural environments, including grain fields, cultivated pastures and rangeland. Feeding damage includes leaf notching and stripping. More extensive damage is caused when stems are severed below the heads of mature and maturing crops. The migratory grasshopper will also feed on dried plant material when accessible. The migratory grasshopper is one of a few species of grasshopper that can cause economic yield loss to prairie crops.
Migratory grasshopper adults grow up to 23-28 mm long, with bodies that range from brown to gray. A small black stripe runs across the head, while the hind legs are marked with a series of black bands. Nymphs are a mottled gray and like the adults, have a black stripe running across the head.
Migratory grasshopper nymphs and adults, albino and normal (AAFC)
Native to North America, the wheat stem sawfly is an economic pest depending on spring and durum wheat as its main crop hosts. These insects also target winter wheat, rye, grain corn and barley, in addition to feeding on native grass species. It is interesting to note that wheat stem sawflies do not feed on oat crops, as the plant is toxic to these insects.
Wheat stem sawfly larvae feed on the pith of plant stems, impacting crop yield and quality. As these host plants mature, the larvae travel down the stem to its base, where “V” shaped notches are cut into the stem a little above ground level. These notches leave plants vulnerable to collapsing, at which point nothing can be harvested. Because wheat stem sawflies also breed and develop on native grass species, economic damage is more prevalent around crop margins where these plants crossover.
Wheat stem sawfly larva (AAFC)
Adult wheat stem sawflies are 8–13 mm long with a wasp-like resemblance, due to their black body and yellow legs. Females have an egg-laying organ (an ovipositor) that extends from their abdomen. When resting on plant stems, these insects will point their heads downward. Mature larvae are 13 mm long and resemble whitish worms with brown heads.
Native to Europe, pea aphids were discovered in Ontario during the late 1800s and continued west into the Prairie region. True to their name, pea aphids consume legumes like field peas, alfalfa, broad beans, chickpeas, lentils and clover. Overwintering as eggs on perennial legumes like alfalfa and clover, pea aphids reproduce asexually until winged females migrate to summer crop hosts to generate several new generations over the growing season.
Pea aphid damage to peas occurs when the insects feed during the flowering and early pod stage, resulting in reduced crop yield due to delayed seed formation and smaller seed size. In alfalfa crops, pea aphids feed on the stems and expanding leaves, stunting overall plant growth and causing the leaves to yellow. Infested alfalfa is more susceptible to cold damage during the winter months.
Adults are long-legged and pear-shaped, between 3-4 millimetres long. Colour varies between light to dark green, and each antennal segment is tipped with a black band. Pea aphid nymphs have a similar appearance but are somewhat smaller.
In 2016, entomologists on the Canadian Prairies identified a previously unknown species of midge while conducting field experiments in northeastern Saskatchewan. The new midge was described in 2019 and is named Contarinia brassicola Sinclair (Diptera: Cecidomyiidae). It is known unofficially as the canola flower midge, although its host range includes mustard varieties.
Swede midge (Bugwood)
The full extent of the host range of canola flower midge has yet to be studied. Field surveys conducted between 2017 and 2019 found that the canola flower midge is widely distributed in Alberta, Saskatchewan, and Manitoba, with some pockets of higher population densities (i.e., northeastern Saskatchewan). The canola flower midge is morphologically similar to the swede midge: a doppelganger insect that damages the same field crops that canola flower midge does, as well as a variety of cruciferous vegetables (e.g., cabbage, cauliflower, Brussels sprouts) and Brassica weeds. Both species have much in common, but differences in the type of plant damage they inflect can help distinguish between the two.
Canola flower midge damage (AAFC)
Neither insect poses a threat to crops in their adult form, but both species have larvae that cause damage to their host plants. Canola flower midge larvae consume individual canola buds, resulting in characteristic galled flowers. In comparison, swede midge larvae are known to attack and consume plant material at any growing point on their host plants, affecting normal plant development.
Canola flower midge damage
Swede midge damage
Both midge species are quite similar in their physical characteristics. Adults are delicate, 2–5 mm long flies ranging in colour from light brown to grey. These insects have long legs, long beaded antennae and sparse venation on their wings. Larvae grow between 3–4 mm long. Young larvae are semi-translucent when they hatch and turn yellow as they mature.
Diamondback moth (Alberta Agriculture and Rural Development)
Diamondback moths are a migratory invasive species. Each spring, adult populations migrate northward to the Canadian Prairies on wind currents from infested regions in the southern or western USA. Upon arrival to the Prairies, migrant diamondback moths begin to reproduce, resulting in non-migrant populations that may have three or four generations during the growing season. Host plants include canola, mustard and other cruciferous vegetables and weeds.
Diamondback moths lay their eggs on leaves. Hatchling larvae tunnel into the leaves, later emerging to the surface to feed. Damage begins as shot holes and eventually expands to complete skeletonization, leaving only the leaf veins. Larvae also feed on flowers and strip the surface of developing pods and stems. Damage can lower seed quality and crop yield.
Diamondback moth damage (AAFC)
Adults are active moths measuring 12 millimetres long with an 18-20 millimetre wingspan. When at rest, the forewings form a diamond-shaped pattern along the mid-line. Mature larvae are 8-millimetre-long green caterpillars. Terminal prolegs extend backwards, resembling a fork. When disturbed, caterpillars drop towards the ground on a silken thread to avoid harm.
Diamondback moth larva (Alberta Agriculture and Rural Development)
On the Canadian prairies, there are several native lygus bug species that cause crop damage including Lygus borealis, L. keltoni, pale legume bug (L. elisus), tarnished plant bug (L. lineolaris) and western tarnished plant bug (L. hesperus). The species vary by preferred host plants, region, and seasonally. These insects feed on both cultivated and wild plants such as canola, alfalfa, soybeans, sunflowers, other crop plants and weeds.
Adult and nymph lygus bugs have mouthparts that allow them to pierce and suck liquids out of their plant hosts. Their desired meal usually includes new growth and reproductive parts such as buds, flowers and young seeds. Having punctured the plant, lygus bugs will inject digestive enzymes and suck out the plant juices. Crop damage includes buds and flowers falling off, incomplete seed pod maturation, misshapen fruit and seeds that collapse and shrink.
Adult lygus bugs are 6 millimetres (1/4 inch) long and vary in colour, ranging between pale green to reddish, brown to black, and uniform to mottled. A distinct triangular or V-shaped marking on the upper centre of their backs and wingtips is also present and can be used to distinguish them from other Hemiptera. Mature nymphs share similar colouration to adults, but with five black dots on their thorax and abdomen.
Cabbage seedpod weevil (Alberta Agriculture and Rural Development)
First discovered in the Prairie region during the 1990s, the cabbage seedpod weevil is a pest in both its adult and larval stages. Cabbage seedpod weevils emerge from overwintering in the spring as soil temperatures warm, and utilize plants like canola, brown and wild mustard to sustain larval development.
Both adult and larval stages can cause crop damage. As adults, cabbage seedpod weevils can cause canola flower budblasting as they feed on developing flowers, and later in the season their appetites will turn to canola pods. However, it is the cabbage seedpod weevil larvae causes the most damage. During their development, these larvae will bore into seed pods and consume the seeds within. Infested pods are more prone to shattering and are more susceptible to fungal infections.
Cabbage seedpod weevil damage to canola (AAFC)
Adult cabbage seedpod weevils are 3–4 mm long with a long narrow snout. When disturbed, these insects “play dead,” resuming activity when the perceived threat has passed. Mature larvae are 2–3 mm long with a whitish body, brown head and anal plate, and 3 pairs of thoracic legs.
This week’s Insect of the Week is the wheat midge. Found around the globe where wheat is grown, these small insects can pose a big problem for producers. Sizeable crop damage has been attributed to wheat midge populations across the Prairies, where it feeds on spring, winter and durum wheat, as well as triticale and spring rye.
Crop damage occurs when the wheat midge is in its larval stage. Once hatched, the wheat midge larvae eat developing wheat kernels, causing shrivelled, misshapen, cracked or scared kernels. This damage isn’t apparent at a glance and developing seeds must be inspected within the glume. Losing wheat kernels will lower crop yield, while damaged kernels will impact the grade given to the harvested wheat. The Canadian Grain Commission allows midge damage between two and five percent prior to impacting the assigned grade.
Wheat midge adult (AAFC)
Adult wheat midges are delicate orange flies that grow to 2–3 mm long, with large black eyes and long legs and antennae in relation to their otherwise small size. Mature larvae grow to 2–3 mm long. Young larvae begin as translucent white maggots and turn bright orange during the maturation process.
This week’s Insect of the Week is the bertha armyworm (Mamestra configurata), a crop pest with the potential to do serious damage when populations run high. Though these insects are harmless to crops as adults, bertha armyworm larvae primarily consume canola, mustard, and alfalfa. Larvae may also consume plants like flax, peas and potatoes. The bertha armyworm is prevalent across the Prairies.
Prior to reaching their mature larval size, bertha armyworms feed on the underside of leaves. In canola and other plants that drop their leaves prior to the bertha armyworms’ larval maturation, the growing larvae move on to eat seed pods, stripping the pods and in extreme cases, consuming the seeds inside them. Even when the seed pods are not eaten through, stripped pods risk shattering and can hinder crop development.
bertha armyworm damage to seed pods (AAFC)
Adults are 20 millimeters long moths with a greyish body and 40 mm wingspan. Wing markings on the forewing include prominent white, kidney-shaped markings near the midpoint, and an olive and white irregular marking extending along the wing tip. Mature larvae are 40 mm long black (though sometimes light green or light brown) caterpillars with a light brown head and an orange stripe along each side, with three broken white lines down their backs.
bertha armyworm moth (Alberta Agriculture and Rural Development)
This week’s Insect of the Week is the cereal leaf beetle (Oulema melanopus). Wheat is their preferred host, but they also feed on oat, barley, corn, rye, triticale, reed canary grass, ryegrass, fescue, wild oat, millet and other grasses. Adults and larvae feed on the leaf tissue of host plants. Yield quality and quantity is decreased if the flag leaf is stripped. It is also interesting to note that larvae carry all their own fecal waste with them as protection from predators and parasitoids.
Cereal leaf beetle damage (Bugwood, Bob Hammon)
Adults are 6-8 millimeters (0.25-0.31 inches) long with reddish legs and thorax (middle section between head and abdomen) and metallic bluish-black head and elytra (wing coverings). Mature larvae are 4-5 mm long (0.16-0.20 inches) with a hump-back body.
This week’s “Insect of the Week” is the Pea Leaf Weevil. Larval hosts are field peas and faba beans. Adults can spread to other cultivated and wild legumes, such as alfalfa, beans and lentils. Each adult female lays up to 300 eggs in one summer! The eggs hatch in the soil near developing plants and larvae move to feed on nitrogen-fixing nodules. This results in partial or complete inhibition of nitrogen fixation by the plant, causing poor plant growth. Adults feed on leaves and growing points of seedlings, causing notches in leaf margins.
Adult pea leaf weevil damage, showing crescent shaped notches on the leaf margin (AAFC)
The pea leaf weevil is a slender greyish-brown insect measuring approximately 5 mm in length. These insects can be distinguished by three light-coloured stripes extending length-wise down the thorax and sometimes the abdomen. All species of Sitona, including the pea leaf weevil, have a short snout. Mature larva grow up to 3.5-5.5 mm long, and are legless and c-shaped with a brown head.
This week’s instalment is a sneak peak at the soon-to-be published manual “Field Guide of Pest Wireworms in Canadian Prairie Crop Production,” written by Haley Catton, Wim van Herk, Julien Saguez, and Erl Svendsen! (stay tuned to this channel)
Wireworms are soil-dwelling insects that have challenged crop production on the Canadian Prairies since farming began in this region. They damage crops by feeding on seeds, roots or lower stems of almost all field crops, and are especially damaging to cereals. Since wireworms are often the only reason growers use insecticide-treated seed in cereals on the Prairies, understanding more about these pests can save costs and reduce unnecessary pesticide use.
Despite their common name and worm-like appearance, wireworms are not actually “worms.” Rather, they are the larval stage of a group of beetles called click beetles (Elateridae family). Their “clicking” is a defensive behaviour that when placed on their backs, projects them up to 30 centimetres (12 inches) or more into the air to escape danger and literally get them back on their legs
Selatosomus aeripennis destructor, or the Prairie grain wireworm, is the largest of Prairie pest wireworms, reaching up to 23 millimetres (1 inch). It is hard-bodied, segmented and yellowish in colour, with three pairs of legs. Adults are 8-13 mm long, black, hairless and have distinct hind angles.
In canola, the most common flea beetles are either bluish black (crucifer flea beetle or Phyllotreta cruciferae) or black with two wavy yellow lines running down the length of its back (striped flea beetle or P. striolata). They overwinter as adults under plant material along field margins and females lay eggs in the soil near host plants.
Striped and crucifer flea beetles feed on canola, mustard and related cruciferous plants and weeds. Canola is highly susceptible to feeding damage at the cotyledon stage – damage appears as ‘shot-holes’ in cotyledon leaves. Flea beetles also feed on stems and very young seedlings may wilt or break off under windy or damp conditions. New generation adults feed on maturing pods late in the summer. Remember, the Action Threshold for flea beetles on canola is when 25% of cotyledon leaf area is consumed (see post from 2019 on estimating flea beetle damage and action threshold and the Flea Beetle Monitoring Protocol).
According Dr. Tyler Wist (@TylerWist1), who makes it his business to know, striped flea beetles are already active.
For many, seed isn’t in the ground yet, but cutworms may be in the soil ready for when it does. So the time to start scouting for cutworms is now! Even if it is too wet to seed, consider checking volunteer plants for cutworms or feeding damage. General cutworm monitoring protocols can be found on the Monitoring Protocols page.
While they may be related and share many similarities, cutworms are not all the same, nor cause the same kind of damage. For example, the armyworm (Mythimna unipuncta) is a climbing cutworm and feeds on leaves. In contrast, young pale western cutworms (Agrotis orthogonia) feed on the surface of newly-emerging shoots and furled leaves of young plants causing small holes and older larvae sever plants just below the soil surface and occasionally pull and eat severed plants underground. In addition, there is likely more than one cutworm species present in your field.
As the growing season winds down, we are wrapping up our summer series with an Insect of the Week doubleheader: one post featuring both sunflower and triticale pests!
Sunflowers are an eye-catching plant with seeds that have numerous uses: as snacks, as birdseed, and as the raw material to produce sunflower oil.
Sunflowers — AAFC
While sunflowers are grown across the Prairie region, the bulk are grown in Manitoba. In fact, almost 90% of Canadian sunflower production took place in Manitoba in 2019. Over the same year, sunflowers were seeded across 28,000 hectares (69,300 acres) in the Prairies, producing 59,000 metric tonnes (65,000 US tons).
Sunflower field — AAFC
Triticale is the first man-made crop species, and was initially produced through the hybridization of wheat and rye to create this new cereal.
Triticale cc by 2.0 Jean Weber
Though its origins date back to 19th-century Scotland and Germany, triticale development didn’t begin in Canada until researchers at the University of Manitoba started to breed this cereal crop in 1954. Still grown in the Prairie provinces, triticale is utilized as a food source for both humans and animals. In 2019, triticale was seeded across 42,000 hectares (103,700 acres) across the Prairie region. The resulting harvest produced 63,900 metric tonnes (70,400 US tons).
This week’s Insect of the Week feature crop is soybean, a common crop in Eastern Canada that has become more popular in the Prairie region over the past decade.
Soybeans – AAFC
Despite being a recent crop to Western Canada, soybean cultivation in Alberta, Saskatchewan and Manitoba contributed 20% to the national production total in 2019. Ongoing research is being conducted to develop new plant varieties that are better suited to the short growing season and low temperatures characteristic to the Canadian Prairies. In 2019, soybeans where seeded over 658,200 hectares (1.6 million acres) across the Prairie Region, producing 1.2 million metric tonnes (almost 1.4 million US tons).
This week’s Insect of the Week feature crop is is rye, a cold and drought resistant grain with various uses, including bread and cereal production, and brewing and malting. Our feature entomologist this week is Haley Catton.
Rye – AAFC
A versatile crop, rye grown in the Prairie region has numerous uses, including animal feed production, bread and cereal production and brewing and malting. Rye can also be used as a cover and forage crop. Like wheat, rye comes in winter and spring varieties, with winter rye remaining the most popular across Western Canada. In 2019, rye was grown over 114,100 hectares (281,700 acres) in the Prairies, producing 262,200 metric tonnes (289,000 US tons).
How do you contribute in insect monitoring or surveillance on the Prairies?
My team and I often work on developing and refining monitoring methods for certain pests (e.g. wireworms). But, for the past few years we have actively been monitoring one particular tiny little insect – the parasitic wasp T. julis, a natural enemy of the cereal leaf beetle. These beneficial wasps are so small that they are easy to miss with the naked eye, only 2-3 mm long in their adult form! We track them by cutting open cereal leaf beetle larvae to see if they are parasitized. We can find 5-20 little T. julis larvae inside a single cereal leaf beetle larva! For next year, we ask that anyone on the Prairies who sees cereal leaf beetle larvae to send us a sample of 10-30 larvae so we can dissect them. We will tell you if T. julis is on the scene and contributing to management of this potentially damaging pest.
In your opinion, what is the most interesting field crop pest on the Prairies?
That’s tough to pick, all of them are interesting in their own way. But if I have to choose, it will be wireworm. This is a pest made up of several species, with long life spans, lots of host crops, and different behaviours. They can go without food for at least a year, and even moult to become smaller in times of stress. They are a formidable pest, but the more I learn about them, the more interesting the story becomes.
What is your favourite beneficial insect?
Another tough choice. T. julis is pretty spectacular, how it finds its host so effectively, a true “seek and destroy” biological control insect, or Field Hero. We think T. julis is a big reason why cereal leaf beetle has not become a major pest on the Prairies, but that is hard to prove when it is tough to even find larvae to dissect! This “disappearance” phenomenon is a big problem in biological control. When beneficial insects are very successful, the pests are no longer noticeable, and therefore less on people’s minds. The value of the beneficial insects therefore becomes “behind the scenes”, and can be overlooked. This is why more research and awareness are needed on the value and efficacy of beneficial insects, so they can considered and protected.
Tell us about an important/interesting project you are working on right now.
I’m just finishing up a 3-year project on wireworms (funded by AWC and WGRF), and have learned so much. I am working with a team to produce a wireworm field guide for the Prairies, and it is shaping up to be a really nice document. Expected release later this year!
What tools, platforms, etc. do you use to communicate with your stakeholders?
I love giving presentations, going to field days, and talking to farmers. Also, find me on Twitter (@haleycatton), or reach out by email, haley.catton@agr.gc.ca.
This week’s Insect of the Week feature crop is oat, a plant grown across the Prairies for both food production and livestock feed. Our feature entomologist this week is Héctor Cárcamo.
Oat – AAFC
A versatile food and feed crop, almost 90% of Canadian oat production takes place across Manitoba, Saskatchewan and Alberta. In 2019 Canada was the world’s third largest oat producer, and number one oat exporter. In the same year, total Prairie production seeded over 1.3 million hectares (3.2 million acres) was over 3.8 million metric tonnes (4.2 million US tons).
Name: Héctor Cárcamo Affiliation: AAFC, Lethbridge Research and Development Centre Contact Information: hector.carcamo@agr.gc.ca
How do you contribute in insect monitoring or surveillance on the Prairies?
I contribute by helping to develop survey protocols for resurging native insect pests (wheat stem sawfly, 2003) or new invasive pests (pea leaf weevil, 2005; cereal leaf beetle, 2007). With my team we also conduct surveys to tackle research questions such as farm threshold validations or landscape studies for lygus bugs, cabbage seedpod weevil and cereal leaf beetle. Finally, I collaborate with various researchers in the writing of scientific articles from survey data.
In your opinion, what is the most interesting field crop pest on the Prairies?
It is difficult to name just one! I really like the wheat stem sawfly because it is so well studied and this allows us to ask more refined ecological questions. Plus it forces us to use non-chemical methods to manage it. But if I had to choose only one to work on…I would pick lygus bugs because they are an extremely challenging and complex pest with populations that can increase rapidly. It seems to be almost ‘unpredictable”! Also it is highly polyphagous and as a species complex, extremely widespread geographically – the tarnished plant bug ranges from Guatemala to Alaska!
What is your favourite beneficial insect?
Well, this is an easy one: a carabid ground beetle of course, my Twitter name gives this one away: @hectorcarabido! Why: because they are so diverse, easy to catch and easy to identify to species. They are also very popular so it is easy to start a conversation over carabid beetles with most entomologists.
Tell us about an important/interesting project you are working on right now.
I am excited about biological control and I am currently leading a national study on biocontrol of cabbage seedpod weevil and I am also equally excited to start the one that got delayed due to COVID-19: A survey of parasitism of lygus nymphs in emerging and established crops.
What tools, platforms, etc. do you use to communicate with your stakeholders?
I regularly do interviews with the farm media and work with the technology transfer platforms used by the various commodity associations that fund our research. I have also contributed to our AAFC fact sheets or other technology transfer publications. Recently I have started to use Twitter and I have participated regularly in the weekly #abbugchat.
This week’s Insect of the Week featured crop is sweet clover: a soil-building, weed suppressing legume. Our feature entomologist this week is Sean Prager.
Sweet clover cc by 2.0 Phil Gayton
Native to Turkey, Canadian sweet clover includes plants developed from Spanish and Siberian sources. Tolerant to cold, drought and various soil textures, sweet clover is a robust crop that is grown across the Prairies. Sweet clover has a taproot that can grow as deep as 1. 5 metres (5 feet) by the end of spring, adding nitrogen and organic matter to soil. As a forage grazed by livestock, it achieves maximum palatability and feed quality between 25 and 35 centimetres (10-14 inches) in height, as it reaches the bud stage. As sweet clover matures, it loses its palatability. Sweet clover contains a unique chemical called coumarin. When sweet clover is exposed to mold growth, coumarin is converted into the anticoagulant dicoumarol, which poses a risk to livestock consuming contaminated hay or silage. For this reason, proper harvesting of sweet clover for hay or silage is essential.
Name: Sean Michael Prager Affiliation: Department of Plant Sciences, University of Saskatchewan Contact Information: sean.prager@usask.ca 306-361-8525 Agriculture Building, 51 Campus Drive, Saskatoon, SK S7N 5A8
How do you contribute in insect monitoring or surveillance on the Prairies?
I coordinate the Lygus surveys in faba bean as part of the provincial monitoring and survey efforts in Saskatchewan. Our lab also occasionally conducts other studies that result in pest information for crops in the prairies.
In your opinion, what is the most interesting field crop pest on the Prairies?
The first insects I worked on were mosquitoes. Because of that experience, I have always been really interested in disease vectors. On the Prairies, Aster Leafhoppers are a vector and pest that have some pretty neat aspects to their biology. They can be a major problem in canola; although the events are rare. Finally, they are also really useful for many of the ecological questions our lab asks.
What is your favourite beneficial insect?
As a postdoc, I studied a small parasitoid wasp called Aphelinus rhamni. It is a species that parasitizes aphids, especially soybean aphid. It was collected in Asia and has potential as a classical biological control agent.
Tell us about an interesting project you are working on right now.
I think the work we are doing to develop thresholds for aphids in pulse crops will be very useful on the Prairies and is quite interesting. Similarly, the work we have been doing on Lesser clover leaf weevils in red clover has been interesting as well and will hopefully be important to industry.
What tools, platforms, etc. do you use to communicate with your stakeholders?
We use many of the standard tools. My lab has a website (www.pragerlab.ca), a twitter account (@USaskENt), and Instagram. We are more active in some places than others. In addition to that, members of my lab often attend field days and grower meetings.
This week’s Insect of the Week featured crop is clover: a plant used both as a cover crop and in pasture blends. Our feature entomologist this week is Vincent Hervet.
Red clover cc by 2.0 George Hodan
While there are numerous clover species, we will be looking at three clovers that are common across the Prairie region: red clover, white clover, and alsike clover. All are short-lived perennial legumes used for pasture and hay production, with red and white clover also used for silage (in mixture with grasses). All three species are cold-tolerant, though each clover is best suited to its own peak soil conditions. All three clovers are palatable and digestible to livestock, though it’s recommended that clover content in a pasture mix never exceed 30% to avoid bloating in cattle and other livestock. In addition to all this, all three species provide pollen and nectar, and attract insects like the bumblebee.
Name: Vincent Hervet Affiliation: Agriculture and Agri-Food Canada Contact Information: Email: vincent.hervet@agr.gc.ca; Tel: 204-915-6918
How do you contribute in insect monitoring or surveillance on the Prairies?
I was previously involved with the monitoring of cereal leaf beetle, diamondback moth, and cutworms in southern Alberta. I am currently planning a monitoring program for pests of stored seeds across the Canadian Prairies.
In your opinion, what is the most interesting field crop pest on the Prairies?
We can find that all species, pests and non-pests, are fascinating if we look close enough. For example, the cereal leaf beetle belongs in the family commonly known as “leaf beetles” and scientifically known as “Chrysomelidae” (from the Greek word “Chrysos” = gold, an allusion to the shininess of most species). Cereal leaf beetles neatly eat the soft parenchyma tissue between the parallel longitudinal veins of cereal leaves and other grasses. Larvae cover themselves with their own feces and a moist secretion, which is often referred to as the “fecal coat”. It provides them protection and camouflage. Ironically, this fecal coat also attracts the parasitoid Tetrastichus julis, the arch nemesis of the cereal leaf beetle in North America.
What is your favourite beneficial insect?
Rather than a single species my favourite beneficial insect is a group of species: parasitoids. Inconspicuous little critters, they are ubiquitous and represent about 10% of all known insect species on Earth. From Tetrastichus julis that keeps the cereal leaf beetle in check in North America, Bracon cephi that keeps wheat stem sawfly in check on the prairies, Macroglenes penetrans that keeps wheat midge in check where it is established, Cotesia glomerata that keeps imported cabbageworm in check in North America, Diolcogaster claritibia that seems to be keeping diamondback moth for the most part in check in southern Alberta since at least 2010, to an undescribed species of Cotesia that appears to keep the alfalfa looper in check (a system that has not been studied because the alfalfa looper is not a big deal―likely thanks to this unknown parasitoid species), and many more, parasitoids are the true silver bullets against insect pests. Insect pest problems could be brought to an end if we could have one effective parasitoid species for each insect pest species and preserve them.
Tell us about an important project you are working on right now.
I am currently working on the detection and control of the bean weevil in stored beans. The bean weevil is a quarantine species for India, our main importer of beans, and bean prices would increase if we could ensure no bean weevils in shipments. I am currently looking for live bean weevils for research. Please contact me if you encounter any!
What tools, platforms, etc. do you use to communicate with your stakeholders?
This week’s Insect of the Week featured crop is alfalfa: a perennial legume known as “the Queen of Forage Crops.” Our feature entomologist this week is Tyler Wist.
Alfalfa – AAFC
A crop indispensable to Canadian livestock production, alfalfa is a high protein forage used for pasture, hay and silage. Since 1950, improved alfalfa cultivars have been developed for growth in the Prairie region. In particular, Variegated alfalfa is a subspecies developed by cross breeding Flemish alfalfa with Siberian alfalfa. The resulting cultivar is known for both its winter hardiness and resilience to drought and is grown across Western Canada. Because alfalfa is so integral to livestock industries, alfalfa seed is a notable Canadian export, with almost all seed production occurring in Manitoba, Saskatchewan and Alberta.
Name: Tyler Wist Affiliation: Agriculture and Agri-Food Canada Saskatoon Research and Development Centre Contact Information: Tyler.Wist@agr.gc.ca
How do you contribute in insect monitoring or surveillance on the Prairies?
I’m involved in insect surveillance, including a project to ground-truth the use of wind trajectories to predict the arrival of aster leafhoppers (and diamondback moths) in the spring. I also monitor for aphids in cereals and pea crops in July and August as part of projects that I run as a Field Crop Entomologist with AAFC.
In your opinion, what is the most interesting field crop pest on the Prairies?
I’ve always been fascinated by aphids because in North America, our pest species are all female. Unlike the majority of insects, these female aphids are born pregnant and they give birth to live, ready-to eat your crop, clones of themselves. Those freshly-birthed offspring already have little clones of themselves starting to mature within them. Thanks to this reproductive strategy, aphid populations can increase quickly and overwhelm their host plants. Right now I’m really interested in pea aphids and their effect on lentils and faba bean. We had high enough pea aphid pressure in my plots last season (2019) that many of our plots yielded nothing which reinforces that this insect is worth studying in these crops.
What is your favourite beneficial insect?
My favourite beneficial insect is the green lacewing larva, which is a generalist predator, so generalist that one once tried to eat me. It is such a fierce predator that female green lacewings have to lay their eggs on the underside of leaves on stalks so that the first-hatched green lacewing larvae do not eat their siblings! The lacewing larva feeds by piercing it’s prey with huge mandibles, then injects a digestive enzyme that liquefies the prey inside its hard, outer exoskeleton. Once their food is liquefied, the larva proceeds to suck the prey dry until all that remains is an empty shell of the insect prey.
Tell us about an important project you are working on right now.
I’ve alluded to two projects already, one funded by WGRF to look at the origins and arrivals of aster leafhoppers to the prairies and see if they are flying in on the same winds as the diamondback moth and one funded by ADF and WGRF to evaluate the yield loss caused by pea aphids. Another important project is to find alternative wheat resistance against wheat midge so that agriculture is not so heavily reliant on using wheat with the Sm1 gene.
What tools, platforms, etc. do you use to communicate with your stakeholders?
I communicate to stakeholders with reports to funding agencies, PowerPoint presentations at grower/agronomist meetings, using Twitter, email and sometimes even over the phone!
This week’s Insect of the Week feature crop is forage grasses: common Prairie plants know to be robust, adaptive, and tolerant to grazing. Our feature entomologist this week is Chrystel Olivier.
Crested wheatgrass cc by 2.0 Matt Lavin
The total cattle population in the Prairie region is 7.7 million animals: over three times the combined population of Atlantic Canada, according to the 2016 census. In order to feed millions of cattle and other livestock, forage is an important component to Prairie agriculture. Forage grasses include native and nonnative grass species grown for grazing, as well as hay and silage production. Sometimes doubling as cover crops in order to prevent soil erosion and nutrient loss, forage grasses are resilient, multi-purpose crops used to sustain livestock: either as a nutritional source in-pasture or as hay and silage used to supplement or replace grazing during the off-season. Common species include timothy grass, crested wheatgrass, and orchard grass.
How do you contribute in insect monitoring or surveillance on the Prairies?
We are monitoring the aster leafhopper (Macrosteles quadrilineatus) that vectors aster yellow (AY) diseases and two species of flea beetles, the crucifer flea beetle (Phyllotreta cruciferae) and the striped flea beetle (Phyllotreta striolata) that feed on canola seedlings. We monitor for these species throughout SK using sweep nets and sticky cards. We record the emergence dates of the flea beetles in spring and their abundance in spring and fall. We also note when migratory aster leafhoppers arrive in the spring and their rate of AY infection.
In your opinion, what is the most interesting field crop pest on the Prairies?
The most interesting field crop pest is the aster leafhopper. It is a small insect (about 4 mm long) that migrates from the southern US states to the Canadian prairies, carried by the wind. It is an efficient vector of the economically important aster yellow disease. Aster yellow phytoplasma infect over 300 plant species, including canola, cereals and many vegetables grown in Canada. Phytoplasma are fascinating because they modify the feeding and reproduction behavior of their insect vectors to their own advantage. For example, AY-infected aster leafhoppers live longer, lay more eggs and can feed on plants they usually don’t feed on, all to increase spread of the pathogen.
What is your favourite beneficial insect?
My favourite beneficial insects are dragonflies. They are sky acrobats, and can fly in every direction, even backwards.
Tell us about an important project you are working on right now.
An important project I am working on right now investigates if hairy lines of brassicas can be used to protect seedlings from feeding and oviposition of flea beetles, diamond-back moths and aster leafhopper. This project is funded by the Canola Agronomic Research Program (CARP). Trichomes (hairs) are known to deter herbivorous insects and have been used as a deterrent with success in several crops. Recently, natural lines of Brassica napus, and the related Brassica villosa species, that exhibited high level of hairs were identified as potential sources of natural resistance towards flea beetles, diamond-back moths and aster leafhoppers. This project involves both field trials and laboratory-based bioassays.
What tools, platforms, etc. do you use to communicate with your stakeholders?
Communication is mostly via peer-reviewed publications, written reports to the funding agencies, and oral presentations during grower/agronomist meetings and conferences. I often speak about insects to groups of all ages at parks and other community events across Saskatchewan.
This week’s Insect of the Week featured crop is the sugar beet, a plant that has been grown in southern Alberta since 1925. Our feature entomologist this week is James Tansey.
Sugar Beet cc by 2.0 Ulrike Leone
Introduced to the Prairies in the mid-20s, sugar beets are the single 100% Canadian sugar source. A crop that loves heat and water, sugar beets require irrigation to thrive. Alberta produces most of the sugar beet in Canada (only Prairie producer) with the rest produced in Ontario. In 2019, sugar beets were seeded on 11,500 hectares (28,500 acres) in Alberta, producing 520,700 metric tonnes (574,000 US tons). This was a 39% decrease compared to 2018 due to unseasonable cold in September and October.
Name: Dr. James Tansey Affiliation: Saskatchewan Ministry of Agriculture Contact Information: James Tansey PhD Provincial Specialist, Insect/Pest Management Production Technology Crops and Irrigation Branch, Saskatchewan Ministry of Agriculture 3085 Albert Street; Room 125 Regina, Canada S4S 0B1 Business: 306-787-4669 Cell: 306-520-3525
HOW DO YOU CONTRIBUTE IN INSECT MONITORING OR SURVEILLANCE ON THE PRAIRIES?
I help to coordinate and conduct insect surveys in several crops throughout Saskatchewan and coordinate diagnostics with the Crop Protection Laboratory located in Regina.
IN YOUR OPINION, WHAT IS THE MOST INTERESTING FIELD CROP PEST ON THE PRAIRIES?
Predatory midges are very cool. Like flea beetles, there is still so much we do not know about these important insects.
TELL US ABOUT AN IMPORTANT PROJECT YOU ARE WORKING ON RIGHT NOW.
I am working on a project to establish thresholds for pea aphid in field peas and lentils. This project is in collaboration with AAFC and utilizes the expertise of the Redvers, Outlook and Swift Current Agri-ARM sites.
WHAT TOOLS, PLATFORMS, ETC. DO YOU USE TO COMMUNICATE WITH YOUR STAKEHOLDERS?
I communicate with stakeholders at extension meetings, field days, and Crop Diagnostic School and use tools including webinars, Twitter, and the telephone.
This week’s Insect of the Week feature crop is flax, a crop that thrives in cooler environments. Our feature entomologist this week is Boyd Mori.
Flax Field Ian Patterson cc by sa 2.0
Flax is a versatile crop grown across the Canadian Prairies, and is used in cooking, animal nutrition, and industrial production. Since 1994 Canada has been the largest flax producer and exporter in the world (Flax Council of Canada, 2020). In 2019 flax was grown on 375,700 hectares (928,500 acres) across the Prairies, producing 483,000 metric tonnes (532,400 US tons). Just under 80% of that total was grown in Saskatchewan.
Name: Boyd Mori Affiliation: Department of Agricultural, Food and Nutritional Sciences, University of Alberta Contact Information: bmori@ualberta.ca twitter: @BoydMori
How do you contribute in insect monitoring or surveillance on the Prairies?
I actively participate in the PPMN. In my position at the U of A, I help monitor bertha armyworm and wheat midge at sites in North-Central Alberta.Next year, my research group will have a project that will try to verify the source of diamondback moths captured in pheromone traps. We will also be re-evaluating the wheat midge pheromone monitoring system with Dr. Maya Evenden (U of A). In the past, my former research group (AAFC-Saskatoon) along with Dr. Meghan Vankosky ran the survey for the canola flower midge in SK and MB and I occasionally helped with the pea leaf weevil survey in SK. I have also been involved with verifying some of the monitoring protocols used by all members of the PPMN.
In your opinion, what is the most interesting field crop pest on the Prairies?
Probably not a surprise to most, but I am going to have to say the canola flower midge, an insect I helped to recently discover and describe. The canola flower midge was previously mistaken for the swede midge, a significant pest of canola and other cruciferous vegetable crops in Ontario. Luckily, the canola flower midge is not as damaging as the swede midge (at least so far), and we are still trying to determine its overall pest status. What makes it really interesting is that we don’t know where the canola flower midge came from. We don’t know if it is a native or invasive species, although we tend to think it is native to the Prairies. We hypothesize it may have switched hosts to canola as acreage increased over the last 40 years, but we don’t know what is its original host plant was. There is a lot of interesting research to come on this species!
What is your favourite beneficial insect?
I am partial to hover flies (Syrphids). The adult flies are often mistaken for bees due to their colouration, but they are harmless and actually help to pollinate many different plants. The larvae are active predators within crops, feeding on a variety of soft-bodied insects, especially aphids.
Tell us about an important project you are working on right now.
I am currently working on a project with Dr. Hector Carcamo (AAFC-Lethbridge) and Jennifer Otani (AAFC-Beaverlodge) investigating insecticide resistance in alfalfa weevil in southern Alberta. We have identified a few populations with resistance to synthetic pyrethroids and we now have a graduate student, Michelle Reid, whose project will map resistance and also the presence of parasitoids throughout southern Alberta. We don’t see much insecticide resistance on the Prairies compared to other regions of the world, so this is a unique project.
What tools, platforms, etc. do you use to communicate with your stakeholders?
I enjoy giving presentations, speaking with farmers and actively participating in extension events (e.g., CanolaPalooza, WheatStalk, Crop walks, etc.) and AGMs each year. Results of our work is published by industry magazines, blogs and newsletters. You can also reach me directly via email or Twitter (@BoydMori). Hopefully my research group will have a functional website soon too.
This week’s Insect of the Week feature crop is corn, which has become more prominent on the Prairies. Our feature entomologist this week is Maya Evenden (Department of Biological Sciences, University of Alberta).
Corn Crop cc by 2.0 Edwin Ijsman
While the bulk of Canadian corn is grown in Ontario and Quebec, the Prairies are not without robust corn production, split between corn for grain and corn for silage. In 2019, corn was grown on 404,800 hectares (992,300 acres) across the Prairies, producing 5.44 million metric tonnes (6 million US tons). Over three quarters of this amount was corn for silage, and the remainder corn for grain.
Name: Maya Evenden Affiliation: Department of Biological Sciences, University of Alberta Contact Information: mevenden@ualberta.ca; @MayaEvenden on twitter
How do you contribute in insect monitoring or surveillance on the Prairies?
My research group develops semiochemical-based monitoring tools that target insects of environmental and economic impact in Alberta. For field crop pests, we have developed and tested semiochemical-based monitoring tools for 1) diamondback moth; 2) pea leaf weevil; 3) red clover casebearer 4) cutworms and 5) wheat midge.
We also work on other non-target species that are captured in monitoring traps (bycatch). This provides information on biodiversity and community composition of arthropods in managed agroecosystems.
I am an active member of the Prairie Pest Monitoring Network.
In your opinion, what is the most interesting field crop pest on the Prairies?
I am partial to the Bertha armyworm because:
It’s a moth (and I love moths)
Larvae march like an army
It is a native insect that exploits agricultural crops planted in its habitat
Pheromone-based monitoring is useful because moths can be caught before eggs are laid in the field to warn producers of the current season’s feeding damage
What is your favourite beneficial insect?
I like the diamondback moth parasitoid, Diadegma insulare because:
It is a specialist on diamondback moth (although it will parasitize other Lepidoptera)
It tracks diamondback moth migration to the Prairie Provinces
It can result in a high level of parasitism of diamondback moth populations
It is highly susceptible to pesticide applications
Tell us about an important project you are working on right now.
We are currently documenting the biodiversity and abundance of ground beetles in pulse crops in Alberta. We will find out the community composition of ground beetle predators in pulse fields, the landscape features with which they are associated, and what they eat. My PhD student Maggie MacDonald is leading this research and we are collaborating with Dr. Boyd Mori on the assessment of beetle gut content using molecular methods.
What tools, platforms, etc. do you use to communicate with your stakeholders?
We communicate with stakeholders through in-person updates at field days and annual meetings. In addition, we publish updates in grower magazines (i.e. Top Crop Manager), newsletters and grower websites. We communicate with grower organizations through research updates. I also communicate directly with stakeholders through email and twitter @MayaEvenden.
This week’s Insect of the Week feature crop is barley, an important Prairie cereal (and not just because it’s an essential ingredient for beer). Our feature entomologist this week is John Gavloski (Manitoba Agriculture and Resource Development).
Barley Crop cc by 2.0 Ian Britton
Without barley, there would be no beer. And the world wept. Thankfully, plenty of barley is grown on the Prairies, not just for beer but also as feed. Roughly 96% of the barley grown on the Prairies is split equally between Alberta and Saskatchewan. In 2019, total Prairie production on 2.85 million hectares (7.05 million acres) was 9.93 million metric tonnes (10.95 million US tons).
Name: John Gavloski Affiliation: Manitoba Agriculture and Resource DevelopmentContact Information: John.Gavloski@gov.mb.ca, @Johnthebugguy
How do you contribute in insect monitoring or surveillance on the Prairies?
I organize annual monitoring programs for diamondback moth, bertha armyworm and grasshoppers in Manitoba. I am also currently monitoring the distribution and levels of cabbage seedpod weevil and pea leaf weevil in Manitoba.
In your opinion, what is the most interesting field crop pest on the Prairies?
Grasshoppers, as a group of insects, are quite interesting. In Canada there are about 180 species of grasshoppers, but only a few cause economic damage to crops. I have enjoyed the sights, sounds, and tastes of grasshoppers; yes you read that last part correctly! The pest species like dry conditions. In late-spring or early-summer we often start to see species of grasshoppers with colourful and almost butterfly-like hind wings; when they fly you get flashes of orange, yellow, and black. None of these are pest species, but cool to observe. Others are good mimics, and can blend in with sand, gravel or leaves very well. Late in the summer it is always a treat to hear the singing of grasshoppers, especially the katydids, which are not pests and are usually green with long antennae. And yes, I have eaten grasshoppers, at an entomology conference featuring an insect banquet. I did enjoy them – anything cooked in a flavourful sauce is good, but I suggest removing the wings if you ever try them – too much cuticle. I guess this bout of entomophagy makes me and the other entomologists at the banquet natural enemies of grasshoppers.
What is your favourite beneficial insect?
This is a really tough, as there are so many fascinating beneficial insects! Hover flies are a family of flies (Syrphidae) with many beneficial and interesting attributes. They are predators, pollinators, masters of mimicry, and it is fun to watch the larvae feed. There are 539 species of hover flies in Canada. Adults are good pollinators that are great at mimicking wasps and bees, come in a variety of sizes, and can often be seen hovering near flowers. The slug-like, legless larvae of many hover flies feed on aphids by impaling an aphid with its mouthparts, holding it up, sucking the fluids out of the body, and discarding the exoskeleton. It makes for a great show. I try to raise awareness about hover flies so that people know they are not wasps or bees, cannot sting and are beneficial in many ways.
Tell us about an important project you are working on right now.
I am tracking the distribution and densities of cereal leaf beetle in Manitoba. It was first found in the northwest region of Manitoba in 2009. A small parasitic wasp called Tetrastichus julis was introduced shortly after cereal leaf beetles were detected. I have been tracking the spread and densities of both the pest and the parasitoid across Manitoba. Cereal leaf beetle larvae are sent to AAFC-Lethbridge where they are dissected to determine the level of parasitism. If the level is low, parasitoids are sent to me for release in Manitoba in areas where they may be lacking. I will be assessing levels of cereal leaf beetle larvae again this year, and hopefully releasing more wasps if needed.
What tools, platforms, etc. do you use to communicate with your stakeholders?
I enjoy doing presentations for academics, producers, agronomists, and the general public. I co-produce the Manitoba Crop Pest Update from May through August. This is an opportunity to communicate current types and levels of insect activity in Manitoba. I like producing factsheets, for pests and beneficial insects, that are available on our department’s website. An information campaign that has been fun to contribute to is “Field Heroes”, which provides information to help raise awareness and provide information about beneficial insects. Until several of the rural newspapers in Manitoba closed recently, I produced a monthly column called “Incredible Creatures” that several of the rural newspapers carried.
This week’s Insect of the Week feature crop is dry bean, one of a number of important Prairie pulse crops. Our feature entomologist this week is Jennifer Otani (Agriculture and Agri-Food Canada).
Fava Bean Crop cc by 2.0 Phillip Halling
Dry bean, an important pulse crop, has seen modest but steady gains over the last five years. On the Prairies, Manitoba leads in both area (71%) and production (60%) (2019, StatsCan). Total Prairie production was 184,200 tonnes (203,046 US tons) on 96,000 hectares (237,400 acres).
How do you contribute in insect monitoring or surveillance on the Prairies?
The Pest Management Program based at the Beaverlodge Research Farm monitors and studies economic insect pests in annual crops, perennial grasses and legumes grown for seed. Our projects have focused on monitoring Lygus and root maggots in canola, red clover casebearer and clover-feeding weevils in clover seed production systems, and wheat midge. The program also monitors pests and beneficial insects in canola, alfalfa, wheat, clovers and grasses grown throughout the BC and Alberta portions of the Peace River region. Data collection supports the development of integrated pest management strategies suited to the region and supports regional and provincial insect pest surveillance and growers. I am the co-chair of the Prairie Pest Monitoring Network, and have supported the Network for many years as a researcher, collaborator, and editor for the PPMN’s Weekly Update and Blog.
In your opinion, what is the most interesting field crop pest on the Prairies?
I have two – one that’s kept me employed and one that scares me! Lygus bugscontinue to intrigue on so many levels. There are several species (a “complex”), that are native to the Canadian prairies. They affect a diverse range of plants and they can adjust to a region by producing more or less generations per season. My other favourite is the red clover casebearer (Coleophora deauratella) – I have tremendous respect for any larva that carries its home around and can chew through plexiglass glue to escape from cages!
What is your favourite beneficial insect?
I love dragonflies – both the aquatic and aerial life stages are simply amazing! Dragonflies are important indicators of ecosystem health. Both the nymphs and adults are fierce predators. I’m also tremendously fond of the Peristenus formerly known as Otaniaea. After years of collecting, rearing and forwarding beautiful specimens to support Dr. Henri Goulet’s work to revise the genus, he generously named this native braconid parasitoid after me. The species was later synonymized but, after so many years studying this pest-parasitoid complex, I’m still very honoured to have a beneficial wasp that attacks Lygus linked to my name!
Tell us about an important project you are working on right now.
Our program continues to work towards making the most of our samples by addressing species of both pest and beneficial insects. We are fortunate to work in a variety of host crops including canola, wheat, peas, alfalfa, creeping red fescue, plus red and alsike clover. This growing season, we now have an enhanced opportunity to continue more of this work in perennial grasses and legumes grown for seed. It’s important because perennials grown for seed, turf and forage markets are common throughout the region with fields remaining in crop 3-5 years and they may be an important reservoir for beneficial insects who traverse beyond field edges. Projects like these, involving our long-term monitoring and surveying research in both annual and perennial field crops, produce data sets we can direct towards the first iteration of the Beneficial Insects project lead by Dr. Haley Catton. We are working to make multiple years of canola survey data, some of our field plot data, and portions of our natural enemies data available to better define interactions and the economic value associated with the interaction of pests and beneficial insects in our fields.
What tools, platforms, etc. do you use to communicate with your stakeholders?
In addition to normal project reporting and publishing results, I actively support tech-transfer events at regional, provincial and national levels. The Pest Management Program has an unofficial lab Blog (http://insectpestmanagement.blogspot.com) to help communicate our activities to producer-cooperators, collaborators and potential students. I am also responsible for the Prairie Pest Monitoring Network (prairiepest.ca) which is a vital tool used to communicate with the Canadian agricultural industry. I also communicate using Twitter (@Bugs5132) during the growing season to highlight our research activities and the PPMN, often with the hashtags #PPMNblog and #WestCdnAg.
This week’s Insect of the Week feature crops are peas and faba beans, two important Prairie pulse crops. Our feature entomologist this week is Shelley Barkley (Alberta Agriculture and Forestry).
Pea Field cc by 2.0 Gilles San Martin
Peas and faba beans are relative newcomers to Prairie large-scale agriculture. Up until the 70s, a typical crop rotation may have been some combination of cereal and summer fallow. Dr. Al Slinkard was hired by the University of Saskatchewan-Crop Development Centre (CDC) in 1972 as a pulse breeder, starting a major transformation of Prairie agriculture. First came dry peas and lentils followed by many other pulse crops. Now there is a team of four pulse breeders at the CDC to carry on Dr. Slinkard’s legacy. And of course, let’s not forgot about the many federal, provincial, university and private industry Prairie pulse breeders that have come along since the 70s.
In 2019, dry peas were grown on 1.7 million hectares (4.3 million acres) on the Prairies, yielding 4.2 million tonnes (4.6 million US tons). Faba beans were grown (37,300 hectares / 92,100 acres) and yielded 107,000 tonnes (118,000 US tons).
Name: Shelley Barkley Affiliation: Alberta Agriculture and Forestry Contact Information: shelley.barkley@gov.ab.ca, @Megarhyssa
How do you contribute in insect monitoring or surveillance on the Prairies?
I am managing the insect monitoring and surveillance program for Alberta Agriculture and Forestry in 2020.
In your opinion, what is the most interesting field crop pest on the Prairies?
It is not a field crop pest, but lily leaf beetle tops my list. So stunningly beautiful, but so devastating to lilies. I am in a war to bring these animals to a tolerable level in my lily bed without having to resort to removing the lilies.
Of the field crop pests, I think bertha armyworm is very interesting, especially how it has capitalized on the introduction of canola. Bertha armyworm have taught me population dynamics, and shown me biocontrol at work in the field. You can read that stuff in a text book, but once you see it in real life you have a new appreciation for nature…and science fiction movies.
What is your favourite beneficial insect?
Ambush bugs are my favourite. I think this species was a model for dragons on Game of Thrones and other works of dragon fiction. All the bumps and lumps on its head and thorax. And those front legs…if only I could have guns like that!
Tell us about an important project you are working on right now.
Delivering insect survey results to the agriculture industry in AB in a timely fashion is my most important current project. I am supporting the industry to the best of my ability.
What tools, platforms, etc. do you use to communicate with your stakeholders?
Twitter, and email are my go to. I also enjoy sharing my photography.
This week’s Insect of the Week feature crops are chickpea and lentil and Erl Svendsen is our feature ‘entomologist.’
Lentil Plant cc by 3.0 Christiaan Kooyman
Lentils (green, red, black beluga, French green, Spanish brown) and chickpeas (desi, kabuli) are important Prairie crops introduced to the region in the 1970s and 1980s. These crops are good options to include in your rotation. Except for a few acres in Ontario, lentils and chickpeas are grown in Alberta and Saskatchewan, with Saskatchewan accounting for 90% of production. In 2019, lentils were grown on 1.5 million hectares (3.8 million acres) and yielded 2.2 metric tonnes (2.4 US tons). Chickpeas were grown on 160,000 hectares (390,000 acres) and yielded 250,000 metric tonnes (280,000 US tons). Over 70% of production is exported.
How do you contribute in insect monitoring or surveillance on the Prairies?
Full disclosure: I am not an entomologist by any stretch of the imagination. But much of my recent work was been to support the communications efforts by the real entomologists of the network. I was the co-lead for the Cereal Aphid Manager app, and have edited done the layout and design of the recent insect field guides. More recently, I’ve been working with a great team to develop the new PPMN website, to be launched soon. I am also responsible for putting out the Insect of the Week post.
In your opinion, what is the most interesting field crop pest on the Prairies?
Considering I knew very little about the life histories of many of the pest and their natural enemies when I started working the entomologists 7 years ago, it’s hard to pick a favourite. Back to the wall, I would have to say the lowly cutworm. Who knew there were so many pest species with very different behaviours. Which makes them a challenging group to manage.
What is your favourite beneficial insect?
I’ve always had a special place in my heart for ladybird beetle. Not only are they beautiful and brightly coloured (orange with black spots), they are voracious, gobbling down hundreds (if not thousands) of aphids and other soft-bodied pests in their short lifespan. And unlike many other natural enemies, both the adult and the larva are mighty hunters.
Tell us about an important project you are working on right now.
I am working with Drs. Haley Catton, Wim van Herk and Julien Saguez on a new Wireworm Field Guide for the Prairies. It summaries all the wireworm research conducted on the Prairies since the 1910s as well as pulling in relevant research from other regions. And of course there will be high quality images throughout. Look for an announcement and download links later this summer.
What tools, platforms, etc. do you use to communicate with your stakeholders?
In addition to the PPMN blog (new website to be launched soon), I work with the entomologists to develop manuals and factsheets. I use Twitter (@ErlSv) and have a booths at several extension events throughout the year to promote the PPMN and other AAFC research programs.
This week’s Insect of the Week feature crop is wheat (durum, spring and winter) and Dr. Meghan Vankosky is our starring entomologist.
Wheat Field cc by 2.0 Sean MacEntee
Wheat is King on the Prairies and has been since the early 1900s (with recent rivalry for top spot by canola, the Queen of the Prairies). There are many challenges to overcome: droughts, pests, soils and agronomy and scientists and extension specialists have been working alongside farmers to improve the genetics, production practices, equipment and infrastructure. In 2019, despite weather challenges, the area seeded to wheat and the harvest remains impressive:
How do you contribute in insect monitoring or surveillance on the Prairies?
I am a co-chair of the Prairie Pest Monitoring Network. In addition to participating in insect monitoring of cabbage seedpod weevil, pea leaf weevil, and grasshoppers, I help provide supplies for diamondback moth, swede midge, and bertha armyworm monitoring across the prairies. In addition to the Prairie Pest Monitoring Network, I am involved with the Canadian Plant Health Council in the Surveillance Working Group and a member of the new AAFC Prairie Biovigilance Network.
In your opinion, what is the most interesting field crop pest on the Prairies?
The pea leaf weevil is very interesting. I started researching pest management options for pea leaf weevil during my MSc program in 2008. We are still working on this pest and learning so much about it. I like working with this species because it is usually easy to find specimens for lab work, they are fairly large (by insect standards) which makes them easy to handle, and I have to admit that they are kind of cute – for a pest.
What is your favourite beneficial insect?
Parasitoids in general are very cool. I spent a year in southern California working on a biological control program for Asian citrus psyllid. During that time, I worked with two parasitoids and studied how they interact with each other and their host. Of the two, I worked most with Diaphorencyrtus aligarhensis. It is an endoparsitoid that lays its eggs inside its host and kills the host from the inside out. There are many interesting parasitoids on the prairies that help manage field crop pests and I look forward learning more about them.
Tell us about an important project you are working on right now.
I just finished two projects (co-led by Dr. Boyd Mori) studying the newly discovered canola flower midge (Contarinia brassicola). We are currently working on writing papers to describe our work, but in three years we learned a great deal about the distribution of this insect in western Canada, its development, population genetics, and potential impact on canola production.
What tools, platforms, etc. do you use to communicate with your stakeholders?
I use the Prairie Pest Monitoring Network Blog (soon to be website), Twitter, and extension events to communicate research and insect monitoring results. I am getting better about using Twitter, both in terms of posting and replying, and am looking forward to helping with #abbugchat in 2020.
This year, we’re doing things a bit differently for our Insect of the Week. Instead of focussing on a single insect (pest or natural enemy), we’re looking at it from a crop perspective. Each week, we’ll pick a crop and list the insects that attack it along with additional helpful information. The insect list is based on the information found in the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide. The field guide offers information describing lifecycle, damage description, monitoring/scouting strategies, economic thresholds (where available) and control options) for each economic pest.
In addition to an Insect of the Week, we’ll also feature one of the entomologists that help support the PPMN, either directly or indirectly.
This week’s feature crops are the Brassica oilseeds (mustard and canola) and Dr. Owen Olfert is our starring entomologist.
Canola Field cc by 2.0 George Hodan
Canola has been gaining ground over wheat in terms of production area, yield and value since it was first introduced on the Prairies. In 2019, 20.4 million tons (18.5 million tonnes) were harvested from 20.4 million acres (8.3 million hectares). Mustard, typically grown in warmer and drier regions than canola, was grown on 398,000 acres (161,000 hectares) across the Prairies to produce 148,000 US tons (134,000 tonnes) across the prairies.
Diamondback moth – Alberta Agriculture and Forestry
ENTOMOLOGIST OF THE WEEK: Owen Olfert
Name: Owen Olfert Affiliation: Saskatoon Research and Development Centre, Emeritus Contact Information: owen.olfert@agr.gc.ca
How do you contribute to insect monitoring or surveillance on the Prairies?
Before I retired, I was the Chair of the PPMN. In collaboration with provincial, federal and industry colleagues, the PPMN makes decisions on insect priorities, develops standardized monitoring protocols, determines timing of surveillance activities, provides appropriate survey tools to collaborators, conducts field surveys, assembles and analyzes data, drafts and presents visual survey results to the agriculture industry. As an Insect Ecologist, I was involved in all of the field and laboratory activities mentioned above. Over the many years, the crop growing season activities have provided amazing professional opportunities in insect ecology, which overlapped strongly with my farming background. I have been fortunate to explore all of the agro-ecosystems of the Prairies in search of insect populations that threaten field crops.
In your opinion, what is the most interesting field crop pest on the Prairies?
Not to offend other insect groups, but I think grasshoppers (Acrididae) are most interesting! My interest in our prairie grasshopper complex began as a summer student with Dr. Roy Pickford (AAFC-Saskatoon) in the early 1970s. Coincidentally, my first assignment as a research scientist with AAFC involved developing surveillance and management strategies for grasshopper pest species in field crops. Over the years, my colleagues and I have published about 30 scientific papers related to grasshoppers.
What is your favourite beneficial insect?
My favourite is Macroglenes penetrans (Pteromalidae), a parasitoid of wheat midge (Sitodiplosis mosellana). It is the dominant parasitoid of wheat midge in western Canada. It is an egg-larval parasitoid; the female wasp oviposits into the egg of its host. It was discovered very early during the first major outbreak of wheat midge in the early 1980s. All of the pest management tools developed for wheat midge have taken this parasitoid into account. As a result, our estimated total saving in pesticide costs alone due to this parasitoid in the 1990’s was $248.3 million.
Tell us about an important project you are working on right now.
Our most recent project is related to an important agricultural pest – parasitoid – host plant complex, involving wheat midge and its parasitoid mentioned above. The project assesses the interactive population dynamics of the host plant (wheat), wheat midge, and M. penetrans, based on their respective life cycles and weather. These simulation models helped to detail our understanding of the tri-trophic population dynamics. The models will help guide pest management decisions prior to and during the growing season.
What tools, platforms, etc. do you use to communicate with your stakeholders?
In addition to the suite of communication tools used by the PPMN, I still attend conferences and get contacted to conduct interviews by the agricultural news media.
Years ago, I was walking home from the University of Alberta campus on a September evening, watching the ground, as entomologists are wont to do, when I saw a huge insect on its back on the sidewalk. It was just off of a major crosswalk under a streetlight. Upon a quick glance, I knew it was one of two things: a giant water bug or a cockroach. Either way, I needed it for my collection, so I carefully collected it using the only container I had on hand. I say that I “carefully collected” it, because water bugs are known for their painful bite and I did not want to take any risks. From inside the container, it was clear that I had scooped up a water bug.
Giant water bugs (Lethocerus americanus) are true bugs (Hemiptera) that belong to the family Belostomatidae. There are over 150 species of water bugs in the Belostomatidae, but most are quite large (> 2 cm). Belostomatids are usually found in ponds, lakes, or slow moving rivers and streams. They spend most of their time in the water, but disperse between bodies of water by flying (except in species that have reduced wings and are flightless), at which time they may be found around streetlights or porchlights. They are predators of other insects, small fish, snails, amphibians, and other animals that they encounter in the water. Giant water bugs use their forelegs to capture prey and then use their long beak-like proboscis to feed on their prey. First, they inject enzymes into their prey that breakdown prey tissues into a liquid. Then they feast on a liquid lunch by sucking their victim dry. Their bite can be very painful. These ‘toe-biters’ are best avoided, but they are important beneficial insects in aquatic ecosystems.
Giant water bugs can be easily mistaken for adult cockroaches (especially the American cockroach, Periplaneta americana, Blattodea: Blattidae). Both water bugs and cockroaches have large, oval shaped bodies that are usually brown coloured. A casual glance or quick encounter with either may lead to a case of mistaken identity. But, upon closer examination, some key differences are easy to see:
Cockroaches have long, obvious antennae. Water bugs do not appear to have antennae unless closely examined.
The head and eyes of water bugs are visible from above. The head and eyes of cockroaches are hidden underneath the pronotum.
Cockroaches have spiny legs evolved for running and quick movement. All six of their legs look the same. Water bugs have forelegs adapted to grabbing prey (raptorial legs). Their legs are also adapted for swimming and have no obvious spines.
Cockroaches are usually classified as pests by humans, but some provide important ecosystem services (i.e. they are decomposers) and others are television and movie stars (i.e. Madagascar hissing cockroaches).
Giant water bug cc-by-nc 4.0 Christian SchwartzAmerican cockroach cc-by-nc 2.0 K. Schneider
Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus). Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.
Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application. For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.
The case of the innocuous versus the evil twin When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.
Review previously featured insects by visiting the Insect of the Week page.
Hoverflies are un-BEE-lievably good mimics of bees and yellow jacket wasps!
Mimicry is used by insects in several ways. Some insects, like the ambush bug and praying mantis, look like plants. These predators sit very still, blending into their surroundings, and wait very patiently for their unwitting prey to pass by. Other insects, use mimicry to avoid predation, often by taking on the appearance of species with clear markings that are known to be dangerous. Hoverflies (Diptera: Syrphidae) are some of the most convincing mimics of all of the insects. Even experts can have a difficult time distinguishing hoverflies from bees and wasps, especially when working in the field.
Bees (honeybees, solitary bees, native bees; Hymenoptera: Apidae): Bees are important pollinators, usually with distinctive black and yellow strips. Bees have two pairs of wings and are much fuzzier than wasps or hoverflies. Bees have stingers, but are not aggressive under normal circumstances. Some species of bees (e.g. honeybees) have barbed stingers that become lodged inside their victim. When this happens, the stinger is pulled out of the body of the bee and the bee dies. For this reason, bees with barbed stingers only sting as a last resort, in an effort to protect their colony. Bees are beneficial insects that will leave you alone if you leave them alone.
Honeybee cc-by 2.0 Renee Grayson
Yellow jacket wasps (Hymenoptera: Vespidae): Yellow jackets and some of their close relatives have colouring similar to bees. Like bees, wasps have two pairs of wings. Unlike bees, which are usually vegetarians, wasps are carnivores that eat other insects. Thus, wasps are beneficial insects, but they also have a bad reputation for harming people because they scavenge for food at our picnics and barbecues during the summer. Wasps also tend to be aggressive and will sting with little provocation.
Yellow jacket wasp cc-by-nc-nd 2.0 Bryan Jones
Hoverflies (Diptera: Syrphidae): Hoverflies belong to a completely different order of insects than bees and wasps. Like bees, hoverflies are pollinators and are often observed hovering over flowering plants in fields and gardens. Unlike bees and wasps, hoverflies only have one pair of wings. Hoverflies do not have a stinger. They also do not have biting mouthparts, so they can do no harm to people. Hoverflies protect themselves from predators, and people, by mimicking bees and wasps. In addition to pollinating plants, hoverflies provide another important ecosystem service: their larvae are predators of small plant-dwelling insects like aphids!
Syrphid fly cc-by-nc-sa 2.0 Eero Sarkkinen
The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.
Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus). Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.
Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application. For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.
Review previously featured insects by visiting the Insect of the Week page.
Often life choices involve lesser evils. But in the case of lady beetle larva and lacewing larva, they both contribute to the greater good. But which one do you have? Both are voracious aphid, mite, mealy bug, insect egg and other soft bodied insect hunters. In fact, lady beetle larva can consume hundreds of aphids during their development. Lacewing larva are no slouch in that department either. Another name for them is aphidlion and they can consume up to 200 aphids per week.
Green lacewing larva cc by 3.0 Whitney CranshawLadybird beetle larva cc by 3.0 Frank Peairs
While both have the same general tapered alligator body, there are few main characteristics that will help to tell them apart.
For more information about these species and more tips on telling them apart, see our Insect of the Week page).
The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger. Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus). Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.
Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application. For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.
Review previously featured insects by visiting the Insect of the Week page.
The case of the Monarch butterfly vs. Painted Lady butterfly (also Viceroy butterfly) An orange butterfly fluttered by. Was it a Monarch butterfly (Danaus plexippus)? Or a Painted Lady butterfly (Vanessa cardui)? If it’s a Monarch, it is species of Special Concern listed under the Species at Risk Act and is not a crop pest. Instead, it’s larvae feed solely on milkweed (Asclepias spp.), typically found in wetland areas. Painted Lady larvae, on the other hand, feed on a wider range of plants including sunflower, canola, mustard, borage, soybean, Canada thistle, burdock, knapweed, wormwood and many other plant species. While neither species overwinter in Canada, Monarchs have regular migratory routes into Canada from Mexico through the USA; Painted Ladies are accidental tourists that are on occasion blown up from the US. One important distinguishing characteristic is the distinct black band with white dots that outline the wings of Monarchs. Painted Ladies do not have this band; instead they have thin white markings along the scalloped wing edges.
Monarch butterfly (Danaus plexippus) cc by sa 3.0 Kenneth Dwain Harrelson Painted Lady butterfly (Vanessa cardui) cc by 3.0 Jean-Pol Grandmont Viceroy butterflies (Limenitis archippus) cc by 2.0 Benny Mazur
Viceroy butterflies (Limenitis archippus) are even more difficult to tell from Monarchs. Viceroys are smaller than Monarchs and sport a black line running through the middle (side-to-side) of the hindwing. Like the Monarch, Viceroys are not crop pests as their larvae feed exclusively on trees of the willow family (willow, poplar, cottonwood). For more information about Painted Lady butterflies, see the Insect of the Week page and our posts on the annual Monarch butterfly migration. The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.
Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus). Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.
Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application. For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.
Review previously featured insects by visiting the Insect of the Week page.
The case of lygus bug nymphs versus aphids: Small, green, soft-bodied, sucking insects – at first glance they could be either lygus bug nymphs or aphids. But spend a moment and look for the following characteristics, and you’ll be able to tell which pest you are dealing with.
Size: depending on the species, aphids can reach up to 4 mm long, but most will be 1-2 mm. Lygus bug nymphs will be larger, 4-6 mm long
Cornicles (small upright backward-pointing tubes found on the back side at the rear of abdomen): aphids have them, lygus bug nymphs do not. In some aphid species, the cornicles or where they attach to the abdomen are black (e.g. corn aphid, English grain aphid).
Markings: older lygus bug nymphs have five distinct black dots on their thorax and abdomen; aphids do not.
Tarnished plant bug nymph – note five black dots on thorax and abdomen – Scott Bauer, USDA English grain aphid – adult and nymphs – note black cornicles (tubes) sticking out the back – Tyler Wist, AAFC
The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.
Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus). Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.
Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application. For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.
Review previously featured insects by visiting the Insect of the Week page.
