Week 11: Western Bean Cutworm

Meghan Vankosky
Categories
Insect of the Week

Western bean cutworm, Striacosta albicosta, is native to North America, where it has traditionally been found in the United States (western Great Plains, including Idaho, Montana, Colorado, Utah, Arizona, New Mexico, Texas). Since 2000, the range of western bean cutworm has expanded to the east in both the United States and Canada, and is now found in Ontario, Quebec, and Nova Scotia (as of 2017).

Western bean cutworm is not present or established in Alberta, Saskatchewan, or Manitoba.

Larva of western bean cutworm. Photographed by Adam Sisson, Iowa State University, Bugwood.org.

It is important for farmers in western Canada to be on the lookout for western bean cutworm because this insect is a serious pest of corn and of dry edible beans (Phaseolus spp.). Larvae of western bean cutworm feed on developing corn ears and bean pods, resulting in direct injury to the harvested parts of these crop plants. In beans, the first and second instar larvae also feed on the leaves and flowers. In corn, damage can be observed on the silk, as well as the cobs and kernels. Damage caused by western bean cutworm increases the susceptibility of the plants to fungal infection, which can further decrease seed quality and yields.

Adult of western bean cutworm, with distinctive tan-coloured markings on the forewings. Photographed by Adam Sisson, Iowa State University, Bugwood.org.

In the adult stage, male and female western bean cutworm can be distinguished from other cutworm moths by a pale tan band on the leading edge of the forewing and by a spot and comma-shaped mark in the same pale tan colour located near the middle of the forewings. Adult moths are most active in mid- to late July and fly mostly at night. Eggs are laid in masses, with about 50-80 eggs on average. The eggs are white when first laid and darken to a light tan colour and then to a purple colour just before hatching. Larvae, especially from the 4th instar on, are characterized by the presence of 2 black stripes behind the head. The larvae are smooth and fairly hairless.

For more information and pictures, please refer to the Canadian Corn Pest Coalition factsheet and the Ontario Ministry of Agriculture, Food and Agribusiness factsheet on western bean cutworm.

Please report insects or damage resembling western bean cutworm to Dr. Meghan Vankosky (meghan.vankosky@agr.gc.ca).

Information for this Insect of the Week post was summarized from an Open Access paper: Smith, J.L., C.D. Difonozo, T.S. Baute, A.P. Michel, and C.H. Krupke. 2019. Ecology and management of the western bean cutworm (Lepidoptera: Noctuidae) in corn and dry beans – Revision with focus on the Great Lakes Region. Journal of Integrated Pest Management 10: 27 https://doi.org/10.1093/jipm/pmz025

Week 10: Pollen Beetle

Meghan Vankosky
Categories
Insect of the Week

The pollen beetle, Brassicogethes viridescens, also known as the bronzed blossom pollen beetle can be a serious pest of canola. It is native to Europe and is an invasive species in Canada. Pollen beetle is now established in Quebec, Prince Edward Island, and Nova Scotia in eastern Canada. Thus far, pollen beetle has not been detected in the prairie provinces of Alberta, Saskatchewan, or Manitoba.

Adult pollen beetles are quite small, only about 2.5 mm, but can disperse up to 3 km to find host plants. Hosts include canola, mustard, and a variety of cruciferous weeds. In the spring, pollen beetles emerge from overwintering sites and disperse to their host crops. Female pollen beetles lay eggs in buds and larvae develop inside the buds. Larvae can be about 4 mm long when they are ready to pupate, have black heads, and have black spots on each segment of their abdomen. Larvae pupate in the soil and new generation adults emerge in late summer. The adult stage overwinters.

Pollen beetle feeding damage on canola buds. Photographed by Olivia Dorn, AAFC-Charlottetown.

Both adult and larval stages of the pollen beetle can cause damage to canola and other host plants. Adult pollen beetles feed on developing buds, flower parts, and pollen. Adults may also consume the pollen of non-host crops, especially in the spring and late summer. Larvae consume pollen, both from developing buds and from open flowers. Larval damage can significantly reduce seed production.

For more information (and pictures), please check out the pollen beetle pages in Field Crop and Forage Pests and their Natural Enemies in Western Canada available in English and French.

Week 9: European Cherry Fruit Fly

Meghan Vankosky
Categories
Insect of the Week

The most severe insect pest of cherries in Europe is the European cherry fruit fly, Rhagoletis cerasi. It has been detected in North America, in Ontario (2016), New York State (2017) and most recently in Quebec (2022). European cherry fruit fly has not been detected in Manitoba, Saskatchewan, Alberta, or British Columbia.

European cherry fruit fly is regulated as a quarantine pest in Canada. If found, it should be reported to the CFIA.

An adult European cherry fruit fly. Photographed by Alison Morris, bugwood.org.

Suitable host plants of European cherry fruit fly include sour cherry, sweet cherry, and black cherry, as well as honeysuckle and some ornamental cherry species. In the United States, it has been found on barberry, coralberry, dogwood and snowberry.

Adult European cherry fruit flies are typically active between May and July. Female flies lay eggs into suitable host fruits, under the skin. Larvae develop feeding inside the fruit, resulting in unappetizing fruit for human consumption. Larvae drop to the soil to pupate and overwinter in the pupal stage, which can last up to 3 winters.

Cherry fruits with exit holes from European cherry fruit fly larvae and characteristic rotted pits around the oviposition and exit hole sites. Photographed by Alison Morris, bugwood.org.

Adult flies are quite small and can be hard to detect. Cherries and other fruits that have been infested usually have areas of rotten or spoiling flesh around the oviposition site. When cut open, fruits infested with European cherry fruit fly can be identified by characteristic tunneling, resulting from larval feeding.

For more information and pictures of European cherry fruit fly please check out this CFIA factsheet or this article prepared by the Invasive Species Centre.

Week 8: Spotted Wing Drosophila

Meghan Vankosky
Categories
Insect of the Week

Spotted wing drosophila, Drosophila suzukii, is an invasive species that is now found in all 10 Canadian provinces. It was first confirmed to be present in British Columbia in 2009, Alberta in 2010, Manitoba in 2013, and Saskatchewan in 2019. It is still not as widespread in the prairie provinces as in other parts of Canada but is, unfortunately, becoming more common in the prairie region.

Spotted wing drosophila is a significant economic pest of fruits and berries. Unlike other fruit flies that are attracted to ripe or spoiling fruits and vegetables, spotted wing drosophila is capable of laying eggs in fresh, healthy fruits. It is a generalist and is known to feed on fruits in at least 19 plant families.

Adult spotted wing drosophila flies on a raspberry. Photographed by Hannah Burrack, North Carolina State University, Bugwood.org.

Adult spotted wing drosophila are small flies with light brown or dark yellow bodies. There are darker coloured bands on the abdomen and the eyes are dark red. Male flies have grey spots on their wingtips; the wings of female flies do not have spots.

Spotted wing drosophila larva inside a raspberry. Photographed by Hannah Burrack, North Carolina State University, Bugwood.org.

After mating, female flies use their saw-like ovipositor to slice into fresh fruit and then deposit 1-3 eggs into the fruit. Larve develop feeding inside the fruit, causing the fruit to spoil from the inside. It is often difficult to distinguish infested fruit from healthy fruit until after the fruit has been picked and cut open.

Spotted wing drosophila larva inside a blueberry. Photographed by Frank A.  Hale, University of Tennessee, Bugwood.org.

Managing spotted wing drosophila is challenging. Optimal methods for management of spotted wing drosophila in Canada, including biological control, are still being developed and tested. When picking fruit like raspberries and cherries on the prairies where spotted wing drosophila might be present, it is important to quickly clean and store the fruit in the fridge. Cold temperatures help to prevent eggs from hatching and will slow down larval development and feeding activity, helping to preserve infested fruit.

More spotted wing drosophila information (and pictures) is available from the CFIA, Manitoba Agriculture, Government of British Columbia, and the University of Minnesota Extension.

Week 7: Fall Armyworm

Meghan Vankosky
Categories
Insect of the Week

The fall armyworm, Spodoptera frugiperda, is an occasional pest in western Canada. Similar to diamondback moth, the adult stage of this species can migrate into Canada with the aid of winds originating in the United States. So far as we know, fall armyworm cannot withstand cold Canadian winters. As a result, it is not a full-time resident pest in Canada.

An adult fall armyworm moth, photographed by Lyle Buss, University of Florida, Bugwood.org

Fall armyworm adults feed on nectar and do not cause any direct damage to crops. Adults have grey, mottled forewings and light coloured hindwings. The forewings have a patches of white scales near the wingtips. Adult fall armyworm lay eggs on their host plants upon arrival in Canada, usually in May and June. If fall armyworm arrive in Canada early enough, a new generation of adults can lay eggs again starting in late July.

A fall armyworm larva, with three stripes especially noticeable near its head as well as the upside down (or inverted) ‘Y’ shape. Photographed by Russ Ottens, University of Georgia, Bugwood.org

The larvae develop feeding on grasses including cereal and corn crops. Larval feeding damage can affect crop yields. For example, larval feeding can prevent plants from producing normal seed heads or ears of corn. The larvae can vary in colour from green to grey, but the head is dark brown and has an upside down “Y” in white.

In eastern Canada, the Great Lakes and Maritimes Pest Monitoring Network uses pheromone traps to monitor for the arrival and activity of fall armyworm. Instructions for in-field scouting and monitoring for fall armyworm are available from the Ontario Ministry of Agriculture, Food and Agribusiness. More information about fall armyworm is available in Field Crop and Forage Pests and their Natural Enemies in Western Canada available in English and French.

Week 6: Soybean Gall Midge

Meghan Vankosky
Categories
Insect of the Week

A new species of midge was discovered in the Midwestern United States following reports of damage to soybean plants in 2018. The new species, Resseliella maxima, or soybean gall midge is now known to occur in Iowa, Missouri, Nebraska, South Dakota and Minnesota. Soybean gall midge is thought to have been present in these states for almost 10 years before its discovery and identification, based on earlier reports of damage now attributed to soybean gall midge.

Soybean gall midge has not been observed or reported in Canada. However, it is important to be aware of this insect due to its relatively close proximity to soybean growing areas in Canada.

Life History and Identification: Adult soybean gall midge are small flies, about 5 mm long, that have grey or black coloured bodies and black legs with white or yellow coloured stripes. Like swede midge and canola flower midge, the adults are small and difficult to observe. Female soybean gall midge lay eggs soon after emerging and live for less than a week. Eggs are fist laid when soybeans are at the V2 or V3 growth stage (approximately early June) into fissures around the base of the stems. Larvae develop while feeding on stem tissues, interrupting movement of nutrients and water to the rest of the plant. Larval feeding damage also increases the risk of soybean plants contracting diseases.

Larvae of soybean gall midge in the stem of a soybean plant. Photographed by Daren Mueller, Iowa State University, Bugwood.org

Once larval development is complete, the bright orange larvae drop to the soil to pupate. Three generations per growing season have been observed in the Midwestern United States. In late summer, larvae of the last generation overwinter as larvae in the soil and pupate in the spring.

Soybean gall midge damage to soybean crops is most apparent at the edge of fields. Up to 100% yield losses have been observed in the outer 15 m of affected soybean fields studied in Nebraska. The amount of soybean gall midge damage decreases as one moves farther into the interior of infested fields.

Wilted and dying soybean plants as a result of infestation by soybean gall midge. Photographed by Daren Mueller, Iowa State University, Bugwood.org

Because this such a new pest, research to better understand its biology, distribution, and options for its management is still underway.  

Learn more about the soybean gall midge and find more pictures of this pest and the damage it causes to soybean plants by checking out these resources:

You can also keep up-to-date with new information and observations of soybean gall midge range expansion by checking out the Soybean Gall Midge Alert Network and iNaturalist.

Week 5: Swede Midge

Meghan Vankosky
Categories
Insect of the Week

Swede midge, Contarinia nasturtii, is an invasive species in Canada and the United States. Swede midge has been detected by the CFIA in Saskatchewan and Manitoba, but is NOT ESTABLISHED IN THE PRAIRIE REGION and has not been detected in pheromone traps used for monitoring since the CFIA detections in 2007/2008. Swede midge has been found in New Brunswick, Nova Scotia, Prince Edward Island, Ontario, and Quebec. It is well-established in Ontario and Quebec, where it has been extremely damaging to brassica vegetable crops (cabbage, broccoli, kale, cauliflower, etc.) and canola crops.

Swede midge has been found in at least 12 states in the northeastern region of the United States (e.g., Vermont, New York). It has recently been found in Michigan, Wisconsin and Minnesota.

A canola raceme with flower buds damaged by feeding swede midge larvae. Photographed by Jonathon Williams, AAFC-Saskatoon.

Swede Midge Identification and Life History: Adult swede midge are small, grey or brown coloured flies, about 2 mm long. Adults lay eggs on the growing points of their brassicaceous host plants and larval development prevents normal plant development.

An adult swede midge and translucent swede midge larvae on a growing point of a canola plant. Photographed by Jonathon Williams, AAFC-Saskatoon.

Larvae are 2-4 mm long and yellow-coloured when ready to pupate; early instar larvae are smaller and are often translucent. Once larval development is complete, larvae drop to the soil to pupate. There can be multiple generations per growing season. Swede midge can also remain in the pupal stage in the soil for over a year if soil and temperature conditions are not suitable for adult emergence.  

A canola plant from a lab-reared colony of swede midge where the growing points infested with large numbers of swede midge larvae that are nearly ready to pupate. Photographed by Meghan Vankosky, AAFC-Saskatoon.

Swede Midge Monitoring: Pheromone-baited traps are used to monitor for swede midge in Manitoba, Saskatchewan, Alberta, and the Peace River Region of BC. This monitoring program is primarily in place as an early detection system. So far, no swede midge have been caught in pheromone traps set up in the prairie provinces. Results from the 2024 monitoring season are shown below.

As swede midge are moving westward in the United States, it is important to keep monitoring for swede midge in an effort to protect the prairie canola and vegetable industries from this potentially devastating pest.

For more information about swede midge visit:

Week 4: Cabbage Stem Flea Beetle

Meghan Vankosky
Categories
Insect of the Week

Unfortunately, prairie canola farmers are very familiar with striped and crucifer flea beetles and the damage they cause.

Striped (above) and crucifer (below) flea beetles and damage symptoms caused by these beetles to the foliage of brassica plants. Both species are established and often are considered pests in Canadian agroecosystems. Photographed by Meghan Vankosky, AAFC-Saskatoon.

In Europe, the cabbage stem flea beetle (Psylliodes chrysocephalus) is known as the most serious pest of oilseed rape, especially winter oilseed rape. Cabbage stem flea beetle can also affect the yield and marketability of brassica vegetables (e.g., kale, cabbage). Managing cabbage stem flea beetles in the United Kingdom is challenging because this species is resistant to pyrethroid insecticides and neonicotinoids are no longer registered for use in Europe.

Cabbage stem flea beetle is not established in Canada.

Cabbage stem beetle can be extremely damaging to brassica crops and can be very difficult to manage. As a result, it is important that we prevent cabbage stem flea beetle from becoming established in Canada.

Life cycle in United Kingdom: Adults of the cabbage stem flea beetle emerge from the pupal stage in early summer (June-July). At this time, adults consume foliage of the host plant. When temperatures are hot in August, adult cabbage stem flea beetles undergo a period of ‘rest’ or aestivation (i.e., summer diapause). Once temperatures have moderated, adults disperse back to the oilseed rape crops from their aestivation sites, continue to feed on host plant leaves and begin to mate.

Egg laying occurs from September to December. As long as temperatures remain above 3°C, eggs will hatch and larval feeding will occur between October and February. The larvae of cabbage stem flea beetles feed in the petioles of the host plant leaves and in the stems of the plants. Larval feeding reduces the vigour of the plants; severe infestations can result in yield losses and plant death. Larval feeding damage increases in March and April when temperatures increase in spring then pupate in the soil near their host plant in May. Adults begin to emerge in June, and the cycle repeats.

For more information about cabbage stem flea beetle, which is not a pest in Canada, please visit the United Kingdom’s Agriculture and Horticulture Development Board cabbage stem flea beetle webpages.

Week 3: Brown Marmorated Stink Bug

Meghan Vankosky
Categories
Insect of the Week

Brown marmorated stink bug, Halyomorpha halys, is invasive to North America. It is not established in the prairie provinces of Canada. Brown marmorated stink bug is established in regions of British Columbia, Ontario, and Quebec.

An adult brown marmorated stink bug. Photographed by Kristie Graham, USDA ARS, bugwood.org

Brown marmorated stink bugs are generalists that will feed on many species of fruits, berries, vegetables, ornamentals (trees, shrubs, flowering plants), and crop plants. Both the adults and nymphs of brown marmorated stink bug feed by inserting their mouthparts into the fruit, stems, or leaves of a host plant. They inject digestive enzymes into the plant and suck up liquid from the plant. The combination of physical and enzymatic damage can result in the formation of necrotic lesions that affect the look and texture of the host plant. Feeding damage can cause flower buds to die, can result in malformed fruits and berries, and shrunken or stained kernels and seeds.

Brown marmorated stink bug eggs and newly hatched nymphs. Photographed by David R. Lance, USDA APHIS PPQ, bugwood.org

Brown marmorated stink bug typically has only one generation per year where it is established in Canada (BC, Ontario, Quebec). Adults overwinter in sheltered areas, including buildings, and begin to emerge from overwintering sites in May and early June. Egg laying usually starts one or two weeks after adult emergence. Egg laying and hatch can be staggered, thus adults, eggs, and nymphs can all be found at the same time for much of the summer.

Brown marmorated stink bugs can be distinguished from other species of stink bugs by the two white bands on the antennae of adults and of late-instar nymphs.

Adult brown marmorated stink bug have two distinct white stripes on the antennae. Photographed by Steven Valley, Oregon Department of Agriculture, bugwood.org

Brown marmorated stink bugs are not regulated by the CFIA. Sightings of brown marmorated stink bugs in Alberta, Saskatchewan, and Manitoba can be reported to the Canadian Plant Health Council using this Google Form.

For more information and pictures of brown marmorated stink bug, please check out the British Columbia Pest Alert and Factsheet or the Government of Ontario brown marmorated stink bug page.

Week 2: Spotted Lanternfly

Meghan Vankosky
Categories
Insect of the Week

Spotted lanternfly is not established in Canada as of May 2025.

Spotted lanternfly is an invasive alien species to North America that originated in Asia. The first established population of spotted lanternfly was detected in the eastern United States in 2014. The distribution of spotted lanternfly has expanded in the United States from the original detection and infestations are now observed in the US close to the Canada-US border. The spotted lanternfly is a CFIA regulated pest. Please report all sightings of spotted lanternfly to the CFIA.

An adult spotted lanternfly, pinned to show off its distinctive colours and markings. Photographed by Bryan Brunet, AAFC-Ottawa.

Spotted Lanternfly Identification and Life Cycle

Eggs are laid in masses about 1 inch (25 mm) long. Egg laying occurs in late summer and through the fall until it gets too cold. Each egg mass contains up to 50 oblong-shaped eggs that are laid in vertical rows. When first laid, the eggs are covered with a protective coating that looks like grey wax or putty. As egg masses age, the coating is lost and the shape of individual eggs becomes more obvious. Spotted lanternfly often lay egg masses on protected surfaces, including the underside of branches and under peeling bark. Eggs can be laid at any location on a tree, from the base of the trunk to the highest branches. Egg masses can also be laid on other smooth surfaces, like vehicles, shipping pallets, and buildings.

Egg masses of spotted lanternfly, with an adult pictured for size comparison. Photographed by Lauren Des Marteaux, AAFC-Harrow.

Eggs hatch in spring. There are 4 nymphal instars that develop through spring and summer. Early instar nymphs are black with white spots. Late instar nymphs are black and red with white spots. The legs of all nymph instars are black with white spots.

Spotted lanternfly nymphs: A) early instar and B) late instar. Photographed by Lawrence Barringer, Pennsylvania Department of Agriculture, bugwood.org.

Adults are active in mid- to late summer. Adults are about 25 mm (1 inch) long. When sitting on a branch, they are approximately 12 mm (0.5 inches) wide. The head and legs are dark brown or black and the abdomen is dark brown with yellow stripes. The forewings are tan-coloured. About 2/3 of the forewings are covered with dark brown spots; the wingtips are characterized by broken brown stripes. The hindwings are bright pink near the body with white/light tan and dark brown/black stripes towards the wing-tips. The bright coloured hindwings are usually covered by the forewings when adult lanternflies are at rest or walking.

Spotted lanternfly are quite unique from other insects found in Canada, helping to make them distinctive and easy to identify.

Spotted lanternfly adults and nymphs are generalists and are known to feed on over 100 different host plants. Their preferred host is Tree of Heaven, which has not been observed or recorded in Alberta, Saskatchewan, or Manitoba. Other hosts include grapevine, fruit trees (cherry, peach, apple, pear, etc.), willow, poplar, and pine. Feeding activity and feeding damage has also been reported on vegetable plants.  

Watch for and report all sightings of spotted lanternfly in Canada!

Everyone can help prevent the establishment of spotted lanternfly in Canada by using visually inspecting trees and plants for spotted lanternfly egg masses, nymphs and adults. For visual inspections:

  1. Identify potential host trees for inspection. The preferred host is Tree of Heaven, which is not reported to occur on the prairies. Other favoured hosts include grapes, apples, plums, cherries, peaches, nectarines, pine, willow, and poplar trees.
  2. In fall and spring, inspect smooth-barked host trees for egg masses, from the ground to the highest point on the tree that you can safely reach. Look for eggs on other smooth surfaces, including vehicles, rocks, lawn furniture, etc. Be especially vigilant and inspect your vehicle if you have travelled to areas of the US where spotted lanternfly is established.
  3. In late spring and summer, inspect host trees for spotted lanternfly nymphs and adults. Nymphs and adults can be easier to observe around dawn and dusk because they migrate up and down trees as the day passes.
  4. Report all observations of spotted lanternfly to the CFIA because spotted lanternfly is a regulated pest in Canada.

For more information about spotted lanternfly, check out the CFIA Factsheet, the USDA Factsheet, and the Penn State Extension management guide.

Week 1: Welcome to Insect of the Week 2025!

Meghan Vankosky
Categories
Insect of the Week

This spring and summer, we will be highlighting insects that might be unfamiliar to you.

They might be insects that have building populations on the prairies, like Hessian fly.

They might be found occasionally in western Canada as migratory pests, like western bean cutworm.

Adult western bean cutworm. Photographed by Adam Sisson, Iowa State University, bugwood.org

They might be found in other parts of Canada but not on the prairies, like swede midge.

An adult swede midge and swede midge larvae developing on a canola plant. Photographed by Jonathon Williams, AAFC-Saskatoon.

Or they might not yet be found or established in Canada. They could be pests in other parts of the world, like cabbage stem flea beetle, or they could be invasive alien species that we need to watch out for in Canada, like spotted lanternfly.

A pinned adult spotted lanternfly, showing the distinct patterns and colours of this invasive alien species. Photographed by Bryan Brunet, AAFC-Ottawa.

Invasive insects and other invasive pests can have significant and negative impacts on agroecosystems and increase the cost of crop production. 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 alien species from becoming established in Canada. 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.

There are also posters for three other regions of Canada: British Columbia (EN/FR), Ontario/Quebec (EN/FR), and the Atlantic Region (EN/FR).

In Week 2 we will feature a very high profile invasive alien species: Spotted lanternfly.  

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