Tag: Canola

Aphids in field crops

Aphid populations can quickly increase at this point in the season and particularly when growing conditions are warm and dry. Access the Provincial Insect Pest Report for Wk12 to remain alert to areas and crops suffering from aphid pest pressure.

**Figure 1**. Pea aphid adults (each 3-4 mm long) and nymph. Photo: M. Dolinski.

Biological and monitoring information (including tips for scouting and economic thresholds) related to aphids in field crops is posted by:
• Manitoba Agriculture (aphids on cereals, aphids on flax, soybean aphid, aphids on peas)
• Saskatchewan Pulse Growers (aphids in pulse crops or access the PDF copy)
• Saskatchewan Flax Development Commission
• Manitoba Pulse and Soybean Growers (soybean aphids: identification, scouting and management or access the PDF copy)
• The Canola Council of Canada’s “Canola Encyclopedia” section on aphids
• or check your provincial commodity group’s insect pest webpages for more detailed information.

Alternatively, several aphid pest species are described in the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) and is accessible as a free downloadable PDF in either English or French on our Field Guides page. PDF copies of the individual pages have been linked below to access quickly:
• Corn leaf aphid or Rhopalosiphum maidis (Fitch)
• English grain aphid or Sitobion (Macrosiphum) avenae (Fabricius)
• Oat-birdcherry aphid or Rhopalosiphum padi (Linnaeus)
• Pea aphid or Acyrthosiphon pisum (Harris)
• Potato aphid or Macrosiphum euphorbiae (Thomas)
• Soybean aphid or Aphis glycines (Matsumura)
• Turnip aphid or Lipaphis erysimi (Kaltenbach)
• Sugar beet root aphid or Pemphigus betae Doane
• Russian wheat aphid or Diuraphis noxia (Mordvilko)

Over the years, both the Weekly Updates and Insect of the Week have included aphid-related information but also important natural enemy details to support in-field scouting. Review the list below so pest and beneficial insects can be distinguished readily when scouting fields:
• Aphidius wasp (Insect of the Week; 2015 Wk15)
• Aphids in canola (Insect of the Week; 2016 Wk13)
• Aphids in cereals (Insect of the Week; 2017 Wk09)
• Cereal aphid manager APP (Weekly Update; 2021 Wk07) that presently is available only for iOS
• Ladybird larva vs. lacewing larva (Insect of the Week; 2019 Wk18)
• Ladybird beetles and mummies (Weekly Update; 2020 Wk15)
• Lygus bug nymphs vs. aphids (Insect of the Week; 2019 Wk16)
• Hoverflies vs. bees vs. yellow jacket wasps (Insect of the Week; 2019 Wk19)
• Pea aphids: a persistent problem for legume growers (Insect of the Week; 2021 Wk12)
• Soybean aphids and aphid annihilating allies (Insect of the Week; 2022 Wk07)
• Syrphid flies (Insect of the Week; 2015 Wk16)

Canola Flower Midge Scouting

Scouting for canola flower midge tends to be easiest as the flowering stage of canola ends and pod development begins. Female canola flower midge lay eggs on developing canola buds and larvae develop inside the buds, resulting in galled flowers that do not open or produce pods.

Although canola flower midge does not appear to occur at densities that cause economic damage, scouting for canola flower midge will help to monitor population growth at the local scale to avoid surprises in the future. The monitoring protocol used during our survey from 2017-2019 is now available online so that everyone can scout for canola flower midge.

Check out the Canola Flower Midge Scouting post from Week 10 in 2023 for pictures of damage caused by this insect and to see a map of canola flower midge distribution.

Compare canola flower midge damage to the closely related Swede midge which was featured as Wk12’s Insect of the Week.

Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.

Bertha armyworm

Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting or review the 2024 Insect of the Week featuring bertha armyworm. Also scan over the 2019 Insect of the Week featuring bertha armyworm and its doppelganger, the clover cutworm!

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm 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.

Diamondback moth

Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre2! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of the diamondback moth.

The economic threshold for immature and flowering canola is 100-150 larvae per metre².

Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture, Saskatchewan Ministry of Agriculture, Alberta Agriculture and Irrigation, and the Prairie Pest Monitoring Network. 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 Field Guides page.

Lygus bug monitoring

On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally.

Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.

Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps. In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.

**Figure 1**. Adult *Lygus lineolaris* (5-6 mm long) (photo: AAFC-Saskatoon).

**Figure 2**. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).

Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.

Scouting tips to keep in mind: Begin monitoring canola when it bolts and continues until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.

How to tell them apart: The 2019 Insect of the Week’s doppelganger for Wk 15 was lygus bug versus the alfalfa plant bug while Wk 16 featured lygus bug nymphs vs. aphids! Both posts include tips to discern the difference between when doing in-field scouting!

Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol. Also refer to the Lygus 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. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes Lygus bugs. The Flax Council of Canada includes Lygus bugs in their Insect Pest downloadable PDF chapter plus the Saskatchewan Pulse Growers summarize Lygus bugs in faba beans.

Week 12: Swede 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.

Please visit the Canola Council of Canada Canola Encyclopedia for more information about swede midge. You can find additional information in previous Insect of the Week posts and in Field Crop and Forage Pests and their Natural Enemies in Western Canada (also available in French).

Diamondback moth

The economic threshold for immature and flowering canola is 100-150 larvae per metre².

Access the Provincial Insect Pest Report for Wk11 for updates for this economic insect pest.

Bertha armyworm

Aphids in field crops

Aphid populations can quickly increase at this point in the season and particularly when growing conditions are warm and dry. Over the years, both the Weekly Updates and Insect of the Week included aphid-related information so here’s a list of these items to access when scouting fields:

• Aphidius wasp (Insect of the Week; 2015 Wk15)
• Aphids in canola (Insect of the Week; 2016 Wk13)
• Aphids in cereals (Insect of the Week; 2017 Wk09)
• Cereal aphid manager APP (Weekly Update; 2021 Wk07) that presently is available only for iOS
• Ladybird larva vs. lacewing larva (Insect of the Week; 2019 Wk18)
• Ladybird beetles and mummies (Weekly Update; 2020 Wk15)
• Lygus bug nymphs vs. aphids (Insect of the Week; 2019 Wk16)
• Hoverflies vs. bees vs. yellow jacket wasps (Insect of the Week; 2019 Wk19)
• Pea aphids: a persistent problem for legume growers (Insect of the Week; 2021 Wk12)
• Soybean aphids and aphid annihilating allies (Insect of the Week; 2022 Wk07)
• Syrphid flies (Insect of the Week; 2015 Wk16)

Lygus bug monitoring

Canola Flower Midge Scouting

Check out the Canola Flower Midge Scouting post from Week 10 in 2023 for pictures of damage caused by this insect and to see a map of canola flower midge distribution.

Week 11: Lygus Bugs

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 Irrigation Lygus 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.

Diamondback moth

The economic threshold for immature and flowering canola is 100-150 larvae per metre².

Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo). Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season, these new adults migrate to overwintering sites beyond the field.

Monitoring:

Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below for reference; retrieved 2024Jul04).

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture, or the Prairie Pest Monitoring Network. Also refer to the cabbage seedpod weevil 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. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes CSPW.

Bertha armyworm

Week 10: Cabbage Seedpod Weevil

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.

The Canola Council of Canada, Alberta Agriculture and Irrigation, and Saskatchewan Ministry of Agriculture have more information about cabbage seedpod weevil and excellent pictures of the damage caused by cabbage seedpod weevil.

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.

Diamondback moth

Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.

The economic threshold for immature and flowering canola is 100-150 larvae per metre². Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture, Saskatchewan Ministry of Agriculture, Alberta Agriculture and Irrigation, and the Prairie Pest Monitoring Network. 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 Field Guides page.

Cabbage seedpod weevil

Monitoring:

Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below for reference; retrieved 2024Jul04).

Bertha armyworm

Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies. Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.

Cabbage seedpod weevil

Monitoring:

Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below for reference; retrieved 2024Jun27).

Diamondback moth

By this week, a second generation of adult diamondback moth should be active in parts of the prairies.

Pheromone-baited delta traps housing sticky cards are used to monitor diamondback moth across the Canadian prairies. Research has shown that cumulative counts > 25 moths indicate elevated risk. In those areas, it then becomes important to scout and assess larval densities.

Bertha armyworm

Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season started the week of June 10, 2024. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.

Week 8: Bertha Armyworm

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., 5^th and 6^th 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.

More information about bertha armyworm is available from the Canola Council of Canada, Alberta Agriculture and Irrigation, Manitoba Agriculture, and the Saskatchewan Ministry of Agriculture. You can also read about bertha armyworm in Field Crop and Forage Pests and their Natural Enemies in Western Canada, available in English and French on the PPMN Field Guides page.

Diamondback moth

The week of May 27, 2024, very mature larvae were retrieved in flixweed in southern Alberta (Barkley, pers. comm. 2024). Thus, a second generation of adult diamondback moth is likely active in southern parts of the prairies.

Pheromone-baited Delta traps housing sticky cards are used to monitor diamondback moth across the Canadian prairies. Research has shown that cumulative counts > 25 moths indicate elevated risk. In those areas, it then becomes important to scout and assess larval densities.

Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre²! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. 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 Field Guides page.

Cabbage seedpod weevil

Monitoring:

Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below as an example; retrieved 2022Jul28).

This image has an empty alt attribute; its file name is 2022Jul28_CSPW-map_AB.png

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and Irrigation, Saskatchewan Agriculture, or the Prairie Pest Monitoring Network. Also refer to the cabbage seedpod weevil 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. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes CSPW.

Bertha armyworm

Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season started the week of June 10, 2024.

Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting or review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm!

Week 7: Diamondback Moth

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.

Diamondback moth

The week of May 27, 2024, very mature larvae were retrieved in flixweed in southern Alberta (Barkley, pers.comm. 2024). Thus, a second generation of adult diamondback moth is likely active in southern parts of the prairies.

Provincial entomologist (Barkley, Tansey, Peru, Gavloski) have kindly provided the following summary for this week:
• Alberta – two traps have caught > 25 adult diamondback moths; one trap deployed in the County of Warner (as of June 15, 2024) and one trap deployed in the County of Grande Prairie (as of June 8, 2024).
• Saskatchewan – 6 RMs have observed cumulative counts >25 (as of June 6, 2024); traps are located near Regina (RM 129), Macroie (RM 285), Buchanan (RM 304), Laura (RM 315), Delisle (RM 345) and Makwa (RM 428). As of June 6, 2024, the highest cumulative count was 61 moths.
• Manitoba – pheromone traps at 20 locations have captured > 25 moths, with cumulative trap catches ranging form 28 to 187. All of the traps with elevated risk are located in the Central, Eastern, South Interlake and North Interlake regions of Manitoba.

Bertha armyworm

Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season started the week of June 10, 2024.

Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.

Diamondback moth

Last week, Shelley Barkley (Alberta Agriculture and Irrigation) swept a flixweed patch in a ditch and found very mature diamondback moth larvae in southern Alberta. Thus, in some parts of the prairies, the first local generation of diamondback moth is nearing completion.

Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts being compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.

Bertha armyworm

Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season will start soon with traps due to be set up the week of June 10, 2024.

Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.

Flea beetles

Two species, the striped and crucifer flea beetles, are the most chronic and economically important insect pests of cruciferous field crops grown across western Canada. Both species are already active so prioritize field scouting in fields of emerging and seedling canola and mustard. All cruciferous crops and plants of any Brassicaceae are similarly attractive and can suffer damage from crucifer (P. cruciferae) and striped flea beetles (P. striolata).

Damage to emerging crops can progress very quickly when flea beetle densities are high, even within the same day! The cotyledon stage of canola is most vulnerable to flea beetle feeding.

Learn more about flea beetle damage in canola by reviewing the Insect of the Week (Wk 2 released May 13, 2024). Review photos of flea beetle feeding damage posted in the Weekly Update (Wk 02 – May 14, 2021) to help assess percent feeding damage and to apply the action threshold of 25 % leaf area of cotyledons. The Canola Council of Canada’s Canola Encyclopedia also features flea beetles along with an excellent visual guide to help estimate feeding damage.

Access biological and pest management information posted by Saskatchewan Agriculture, Manitoba Agriculture, or the Canola Council of Canada’s Canola Encyclopedia. Refer to the flea beetle page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (Philip et al. 2018) as an English-enhanced or French-enhanced version.

Diamondback moth

Earlier this week, Shelley Barkley (Alberta Agriculture and Irrigation) swept a flixweed patch in a ditch and found diamondback moth larvae (Fig. 1) that were nearly ready to pupate! Thus, in some parts of the prairies, the first local generation of diamondback moth is well underway and nearing completion.

**Figure 1.** Diamondback larvae collected using a sweep-net in flixweed growing near Dunmore AB on May 27, 24. Photo: S. Barkley (Alberta Agriculture and Irrigation).

It’s a busy week in the field, so we do not have a full update on diamondback moth trap captures to share this week. Please check out the Provincial Reports for the most up-to-date information available from the diamondback moth pheromone monitoring program.

Bertha armyworm

Based on long-term data for the prairie region, bertha armyworm pupal development should be 30-75% completed by late May in a normal year (Fig. 1).

Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season will be starting soon, with traps likely to be set up the week of June 10, 2024.

Flea beetles

Damage to emerging crops can progress very quickly when flea beetle densities are high, even within the same day! The cotyledon stage of canola is most vulnerable to flea beetle feeding.

Diamondback moth

Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths attracted to pheromone-baited delta traps deployed in fields. Thank you to the many people who deployed and are weekly checking traps across the BC Peace, Alberta, Saskatchewan, and Manitoba! Weekly trap interceptions are observed to generate cumulative counts.

As the season progresses, cumulative count estimates arising from these pheromone traps are broadly categorized to help producers prioritize and time in-field scouting for larvae. Preliminary data from the initial weeks of monitoring includes:

Alberta – So far, two traps in southern Alberta have caught more than 10 moths, one in Mountain View County and one in Kneehill County. Visit Alberta Agriculture and Irrigation’s ‘live’ reporting map for updates through the 2024 growing season.
Saskatchewan – Dr. James Tansey and Carter Peru (Saskatchewan Ministry of Agriculture) shared that traps near Regina (RM129), Makwa (RM561), and Lumsden (RM189) have caught 20-25 adult diamondback moths. Several traps have also caught more than 25 moths so far this monitoring season, including traps near Laura (RM315), Delisle (RM345), Macroie (RM285), and Buchanan (RM304).
Manitoba – Dr. John Gavloski (Manitoba Agriculture) reported that five diamondback moth traps have now captured more than 25 moths in Manitoba. These traps are located in the Central region (2), Eastern region (1) and North Interlake region (2) of the province. So far, the highest cumulative count in a single trap is 69.

Flea beetles

Two species, Phyllotreta striolata and P. cruciferae, are the most chronic and economically important insect pests of cruciferous field crops grown across western Canada. Both species are already active so prioritize field scouting in fields of emerging and seedling canola and mustard. All cruciferous crops and plants of any Brassicaceae are similarly attractive and can suffer damage from crucifer and striped flea beetles.

If flea beetle densities are high, seedling damage levels can advance quickly – even within the same day! The cotyledon stage of canola is vulnerable to flea beetle feeding. To learn more about flea beetle damage in canola, review the current Insect of the Week (Wk 2 released May 13, 2024). Review photos of flea beetle feeding damage posted in the Weekly Update (Wk 02 – May 14, 2021) to help assess percent defoliated and to apply the action threshold of 25 % leaf area of cotyledons. The Canola Council of Canada’s Canola Encyclopedia also features flea beetles along with an excellent visual guide to help estimate feeding damage.

Diamondback moth

Alberta – So far, cumulative trap counts ranged from 0-10 moths with the highest interception rates arising from near Barrhead and Camrose AB. Visit Alberta Agriculture and Irrigation’s ‘live’ reporting map for updates through the 2024 growing season.
Saskatchewan – Dr. James Tansey and Carter Peru (Saskatchewan Ministry of Agriculture) shared results arising the weeks of May 1 and May 8, 2024; cumulative trap catches so far ranged from 0-16 with traps near Navscoy, Lumsden, and Coteau SK reporting the most so far.
Manitoba – Dr. John Gavloski (Manitoba Agriculture) reported that cumulative diamondback moth trap catches ranged from 0-23 for the majority of traps but that two sites reported >25 total moths. One site in the Eastern region has intercepted 33 moths and one trap in the North Interlake region has intercepted 61 moths.

Week 2: Flea Beetles

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.**

Diamondback moth

Alberta – So far, Shelley Barkley (Alberta Agriculture and Irrigation) reported that low numbers of diamondback moth were captured at a few monitoring locations in southern and eastern Alberta and noted the Alberta Agriculture and Irrigation’s ‘live’ reporting map is active for 2024.
Saskatchewan – Dr. James Tansey (Saskatchewan Ministry of Agriculture) also reported that adult diamondback moth were captured at a few locations in Saskatchewan.
Manitoba – Dr. John Gavloski (Manitoba Agriculture) reported that diamondback moth were observed from 13 traps; 3 traps intercepted 10 or above, but no larger counts yet.

Predicted Diamondback Moth Development

In summer 2023, diamondback moth development is well ahead of average. Model simulations to July 16, 2023, indicate that the third generation of non-migrant adults (based on early May arrival dates) is currently occurring across the Canadian prairies (Fig. 1).

**Figure 1. Predicted number of non-migrant generations of diamondback moth (*Plutella xylostella*) expected to have occurred across the Canadian prairies as of July 16, 2023.**

When we ran the model using long term average weather data (based on climate normals), the model output showed that the second generation of diamondback moth would be occurring at this date in a ‘normal’ year (Fig. 2). Above normal temperatures in 2023 have increased the rate of diamondback moth development, resulting in three generations in the time it usually takes for the development of two generations!

**Figure 2. The number of non-migrant generations of diamondback moth (*Plutella xylostella*) expected to have occurred across the Canadian prairies as of July 16, based on climate normal data.**

Some areas of the prairies might be at risk of damage from diamondback moth this summer. Pheromone traps with cumulative counts greater than 25 male moths were located around Cadillac, Rosetown, Makwa, Eatonia, and Swift Current in Saskatchewan, in the Vulcan area in Alberta, and in all regions of Manitoba (data in the July 5 Crop Pest Update). According to the July 19 edition of the Manitoba Crop Pest Update, canola fields in the Plum Coulee, St. Joseph and Dominion City areas of Manitoba had high levels of diamondback moth larvae in the last week. Because diamondback moth can have multiple generations in a single growing season and because the generation time is shorter when temperatures are warm, their populations can build up quickly. Keep scouting for diamondback moth to avoid unpleasant surprises at the end of this summer.

To scout for diamondback moth, estimate the number of diamondback moth larvae per m² at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m². In podded canola, the economic threshold is 200-300 larvae/m². See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

Predicted Grasshopper Development

Model simulations were used to estimate the status of grasshopper development as of July 9, 2023. As a result of warmer than normal temperatures, grasshopper development continues to be well ahead of average. As of July 9. 2023, the average predicted instar for grasshopper populations across the prairies is 4.9, which is significantly greater than the long term average of 3.1 for this time of year. Simulations indicate that 70% of the prairie population should be in the fifth instar or adult stage (Fig. 1).

**Figure 1. Predicted grasshopper (*Melanoplus sanguinipes*) development, presented as average instar, across the Canadian prairies as of July 9, 2023.**

In a ‘normal’ year, we would expect that 57% of the grasshopper population would be in the third or fourth instar in early July (Fig. 2).

Figure 2. In an average year (based on 30-year average weather or climate normals), we expect that about 57% of the grasshopper population would be in the third or fourth instar in early July, as pictured here on the map. In contrast, in 2023, warm weather has significantly sped up the rate of grasshopper development (Fig. 1).

Reports from across the prairies indicate that adult grasshoppers are now occurring. This is much earlier than normal, but agrees with our model simulations, which predict that adult grasshoppers are now occurring across most of the prairies (Fig. 3). Based on earlier than normal appearance of adults, high densities and drought conditions, grasshopper risk may be significant for large areas of Alberta and Saskatchewan as well as southern Manitoba.

**Figure 3. The proportion (%) of the migratory grasshopper (Melanoplus sanguinipes) population expected to be in the adult stage across the Canadian prairies as of July 9, 2023.**

Models and geospatial maps are tools to help time in-field scouting on a regional scale but grasshopper development and population densities can vary even between relatively close locations. Thus, grasshopper populations are best assessed through scouting. Monitor roadsides and field margins to assess the developmental stage and densities of local grasshopper populations.

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture, and Manitoba Agriculture and in the Field Crop and Forage Pests guide.

Diamondback Moth

Diamondback moths are a migratory invasive species; in 2023, the first migratory adults were found in pheromone traps in early May. Thanks to the above average warm weather across most of the prairie region this year, diamondback moth development is well ahead of average. Based on development models and weather to July 2, a third generation of non-migrant adults is expected to be occurring in some parts of the prairies (Fig. 1), with the second generation occurring in nearly all other areas of the prairies (Fig. 1).

Diamondback moth typically have 4 full generations during prairie summers. In an average year, we would expect that the second generation of non-migrant diamondback moth would we widespread right now, NOT the third non-migrant generation (Fig. 2).

Figure 2. Number of non-migrant generations of diamondback moth (*Plutella xylostella*) expected to have occurred across the prairie region by early July in a ‘normal’ year (based on 30-year average or long-term normal weather data).

Some areas of the prairies might be at risk of damage from diamondback moth. Pheromone traps with cumulative counts greater than 25 male moths so far in 2023 are located around Cadillac, Rosetown, Makwa, Eatonia, and Swift Current in Saskatchewan, in the Vulcan area in Alberta, and in all regions of Manitoba (see the July 5 Manitoba Crop Pest Update). In Manitoba, the highest counts of diamondback moths in pheromone traps exceed 200 total moths in the Central and Eastern regions. Because diamondback moth can have multiple generations in a single growing season and because the generation time is shorter when temperatures are warm, their populations can build up quickly. Keep scouting for diamondback moth to avoid unpleasant surprises later this summer.

Bertha Armyworm

Based on model simulations, bertha armyworm development continues to be 7-10 days ahead of normal. Where present, populations of bertha armyworm will largely be in the larval stage (Fig. 1).

The larvae of this generalist moth could be found in canola fields, but also in other crops.

The lifestages of bertha armyworm: A) eggs, B) larva, C) pupa, and D) adult. All pictures taken by Jonathon Williams, AAFC-Saskatoon (please include a photo credit if these pictures are reproduced elsewhere).

The network of pheromone traps across the prairies is reporting low numbers of adults (less than 300 cumulative catch over the last 6 weeks) so far in 2023, including in Manitoba (check out the July 5 Manitoba Crop Pest Update), Saskatchewan, and Alberta. Only one monitoring location (in Manitoba) has caught more than 300 bertha armyworm adults so far this year, suggesting relatively low risk across the prairies. Risk to yield from bertha armyworm increases when cumulative trap catches exceed 300 (300-900 = medium risk, >900 = high risk). Although the pheromone trap network suggests low risk of economic damage from bertha armyworm, it is still important to scout for larvae. For information about scouting, check out the PPMN protocol and the Alberta Agriculture and Irrigation pages.

Predicted Bertha Armyworm Development

Based on model simulations, bertha armyworm development continues to be 7-10 days ahead of normal. Where present, females should have already begun to lay eggs (Fig. 1).

**Figure 1. Proportion (% of total population) of the bertha armyworm (*Mamestra configurata*) population that is expected to be in the egg stage across the Canadian prairies as of June 18, 2023.**

In some areas, first instar larvae (caterpillars) may be present (Fig. 2).

Figure 2. **Proportion (% of total population) of the bertha armyworm (*Mamestra configurata*) population that is expected to be in the larval stage across the Canadian prairies as of June 18, 2023.**

This week there have been some reports of large green caterpillars on canola crops in Alberta and Saskatchewan. The green caterpillars are too advanced in their development to be bertha armyworm. These are more likely to be alfalfa looper or clover cutworm. This week, a Canola Watch quiz challenges us to identify ‘green worms‘ in oilseed crops and provides excellent information about how to tell the difference between bertha armyworm, alfalfa looper, diamondback moth, clover cutworm, and cabbageworm.

Predicted diamondback moth development

Diamondback moths (Plutella xylostella) are a migratory invasive species; after initial migration into the prairies, diamondback moths can have multiple non-migratory generations during the growing season. Diamondback moth development can be rapid during periods of warm weather. Model simulations to June 4, 2023, indicate that the first generation of non-migrant adults (based on early-May arrival dates) is currently occurring across the Canadian prairies. If above-normal temperatures persist, then we may start to see some second-generation diamondback moths next week.

**The life cycle of diamondback moth can rapidly progress from egg (A) to larvae (B and C), to pupae (D) to adults (E). Photo credit: Jonathon Williams, AAFC-Saskatoon.**

On the prairies, we use a network of pheromone traps to detect the first spring appearance of diamondback moths. Now, local scouting is needed to determine if diamondback moth pose a threat to crops. To scout, estimate the number of diamondback moth larvae per m² at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m². In podded canola, the economic threshold is 200-300 larvae/m². See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

Predicted bertha armyworm development

Based on model simulations, development of overwintered bertha armyworm (Mamestra configurata) pupae continues to be significantly ahead of normal for most of the prairies. Bertha armyworm pupae across the prairie region are expected to be at least 90% finished their larval development (Fig. 1); as a result, adults might already be emerging in some areas.

**Figure 1. Predicted bertha armyworm (*Mamestra configurata*) pupal development (%) across the Canadian prairies as of June 4, 2023.**

The bertha armyworm model predicts that adults could already be present in a region between Lethbridge, Alberta and Swift Current, Saskatchewan (Fig. 2). Adult moths may also be flying near Edmonton, Alberta and in the northern limits of the Peace River region (Fig. 2).

Figure 2. The proportion of the bertha armyworm (*Mamestra configurata*) population that is predicted to be in the adult stage (% of total population) across the Canadian prairies as of June 4, 2023.

FLEA BEETLES ARE ALREADY JUMPING INTO ACTION

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.

Adult Striped Flea Beetle – Photo credit: Jonathon Williams, AAFC-Saskatoon

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 2022 PPMN Insect of the Week flea beetle article
Biological and management information from the Saskatchewan Ministry of Agriculture
Biological and management information from Manitoba Agriculture
The Canola Council of Canada’s Canola Encyclopedia
The flea beetle pages in Field Crop and Forage Pests and their Natural Enemies in Canada (Philip et al. 2018), in English or French

Predicted diamondback moth development

Recent warm conditions have resulted in the rapid development of diamondback moth populations. Model simulations to August 14, 2022, indicate that the fourth generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the southern prairies (Fig. 1). DBM development is predicted to be marginally greater in 2022 than expected based on long-term average values (Fig. 2).

Warm conditions during August resulted in rapid development of diamondback moth populations. Model simulations to August 21, 2022, indicate that the fourth generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across most of the prairies (Fig. 1). DBM development is predicted to be marginally greater than long-term average values (Fig. 2).

Figure 2. Long-term predicted number of non-migrant generations of diamondback moth (*Plutella xylostella*) expected to have occurred across the Canadian prairies **as of August 21**, **based on climate normal data**.

In-Field Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 3) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 3. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m² (approximately 2-3 larvae per plant). Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg — Figure 4. Diamondback moth pupa within silken cocoon.

This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png — Figure 5. Adult diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. 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.

Diamondback moth was the Insect of the Week for Wk10 in 2021!

Lygus bug monitoring

Predicted diamondback moth development

In-Field Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Diamondback moth was the Insect of the Week for Wk10 in 2021!

Lygus bug monitoring

Predicted diamondback moth development

Model simulations to August 7, 2022, indicate that the third generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across most of the prairies (Fig. 1). DBM development is predicted to be marginally greater in 2022 than expected based on long-term average values (Fig. 2).

Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths attracted to pheromone-baited delta traps deployed in fields. Weekly trap interceptions are observed to generate cumulative counts. Summaries or maps of cumulative DBM data are available for Manitoba, Saskatchewan and Alberta. These cumulative count estimates are broadly categorized to help producers prioritize and time in-field scouting for larvae.

Diamondback moth was the Insect of the Week for Wk10 in 2021!

Predicted diamondback moth development

Model simulations to July 31, 2022, indicate that the third generation of non-migrant adults (based on mid-May arrival dates) is currently occurring across the southern prairies (Fig. 1). DBM development is predicted to be marginally greater this year than expected based on long-term average values (Fig. 2).

Diamondback moth was the Insect of the Week for Wk10 in 2021!

Predicted diamondback moth development

Model simulations to July 24, 2022, indicate that the third generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the southern prairies (Fig. 1). DBM development is predicted to be marginally greater than long-term average values (Fig. 2).

Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths attracted to pheromone-baited delta traps deployed in fields. Weekly trap interceptions are observed to generate cumulative counts. Summaries or maps of cumulative DBM data are available for Manitoba, Saskatchewan and Alberta. These cumulative count estimates are broadly categorized to help producers prioritize and time in-field scouting for larvae.

Figure 2. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

Diamondback moth was the Insect of the Week for Wk10 in 2021!

Cabbage seedpod weevil monitoring

Monitoring:

Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved 2022Jul28).

CSPW was the Insect of the Week for Wk08 in 2021!

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and Forestry, Saskatchewan Agriculture, or the Prairie Pest Monitoring Network. Also refer to the cabbage seedpod weevil 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. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes CSPW.

Predicted diamondback moth development

Model simulations to July 17, 2022, indicate that the second generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the Canadian prairies (Fig. 1). This week, development of the second generation has expanded across most of the Peace River region and the third generation is predicted to occur in a localized region of southern Manitoba. DBM development is predicted to be similar to average values (Fig. 2).

Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths attracted to pheromone-baited delta traps deployed in fields. Weekly trap interceptions are observed to generate cumulative counts. Summaries or maps of cumulative DBM data are available for Manitoba, Saskatchewan and Alberta. These cumulative count estimates are broadly categorized to help producers prioritize and time in-field scouting for larvae.

Diamondback moth was the Insect of the Week for Wk10 in 2021!

Predicted diamondback moth development

Recent warm conditions should result in the development of DBM populations. Model simulations to July 3, 2022, indicate that the first generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the Canadian prairies and that the second generation is emerging across Manitoba and Saskatchewan (Fig. 1). DBM development is predicted to be similar to average values (Fig. 2).

Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths attracted to pheromone-baited delta traps deployed in fields. Weekly trap interceptions are observed to generate cumulative counts. Summaries or maps of cumulative DBM data are available for Manitoba, Saskatchewan and Alberta. These cumulative count estimates are broadly categorized to help producers prioritize and time in-field scouting for larvae.

Diamondback moth was the Insect of the Week for Wk10 in 2021!

Predicted diamondback moth development

Model simulations to June 26, 2022, indicate that the first generation of non-migrant adults (based on mid May arrival dates) are currently occurring across the Canadian prairies and that the start of the second generation is emerging in southern Manitoba (Fig. 1).

Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths attracted to pheromone-baited delta traps deployed in fields. Weekly trap interceptions are observed to generate cumulative counts. Summaries or maps of cumulative DBM data are available for Manitoba, Saskatchewan and Alberta. These cumulative count estimates are broadly categorized to help producers prioritize and time in-field scouting for larvae.

Diamondback moth was the Insect of the Week for Wk10 in 2021!

Predicted bertha armyworm development

Compared to long-term averages, bertha armyworm (BAW) development has been delayed thus far in the 2022 growing season. Pupal BAW development is progressing across the prairies. This week, pupal development is predicted to complete and adult emergence is expected to occur across most of the prairies (Fig. 1). Adult emergence should have already begun across a region extending from Lethbridge to Regina and north to Saskatoon. Adult emergence near Regina, Saskatchewan (Fig. 2) is predicted to be one week ahead of central Alberta (Fig. 3). Oviposition should begin over the next 7-10 days.

Figure 1. Predicted bertha armyworm (*Mamestra configurata*) pupal development (%) across the Canadian prairies as of June 19, 2022.

Figure 2. Predicted bertha armyworm (*Mamestra configurata*) populations near Regina, Saskatchewan as of June 19, 2022 **(projected to June 30, 2022, based on long-term average conditions)**.

Figure 3. Predicted bertha armyworm (*Mamestra configurata*) populations near Lacombe, Alberta as of June 19, 2022 **(projected to June 30, 2022, based on long-term average conditions)**.

Use the images below (Fig. 4) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.

Figure 4. Stages of bertha armyworm from egg (A), larva (B), pupa (C) to adult (D).
Photos: J. Williams (Agriculture and Agri-Food Canada)

Predicted bertha armyworm development

Pupal development of bertha armyworm (BAW) is progressing across the prairies with the most rapid development occurring across southern and central regions of Alberta and western Saskatchewan (Fig. 1). Over the next week, adults should be emerging across Alberta, Saskatchewan and localized areas in southern Manitoba.

Figure 1. Predicted bertha armyworm (*Mamestra configurata*) pupal development (%) across the Canadian prairies as of June 12, 2022.

Use the images below (Fig. 2) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.

Figure 2. Stages of bertha armyworm from egg (A), larva (B), pupa (C) to adult (D).
Photos: J. Williams (Agriculture and Agri-Food Canada)

Predicted bertha armyworm development

Compared to average development, bertha armyworm (BAW) pupal development in 2022 continues to be delayed for the Peace River region, Manitoba and southern and eastern regions of Saskatchewan (Fig. 1). Pupal development across southern and central Alberta and Saskatchewan is similar to long-term average values. Development in this region is 60-75% complete.

We suggest that BAW pheromone traps be placed in fields when pupal development is 75-80% to ensure that traps are in place prior to emergence of adults. Based on current runs, it is advisable that traps for Alberta and Saskatchewan be placed in fields by the end of this week (June 6-10). Traps should be put out in Manitoba and the Peace River region next week.

Figure 1. Predicted bertha armyworm (*Mamestra configurata*) pupal development (%) across the Canadian prairies as of June 5, 2022.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting or eview the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm!

Predicted bertha armyworm development

When considering average versus in-season pupal development, the current 2022 development of overwintered BAW pupae is expected to be significantly delayed for the Peace River region, Manitoba, and southern and eastern regions of Saskatchewan (Fig. 1). Though somewhat delayed, development of BAW pupae in southern and central Alberta and western Saskatchewan will be similar to average.

We recommend BAW pheromone traps be placed in fields when pupal development is 75-80 % to ensure traps are deployed in advance of the emergence of adults. The weather forecast predicts normal temperatures for the next week. This should advance BAW development with rates becoming similar to long-term average values. Based on current runs, it is advisable that Alberta and Saskatchewan traps be placed in fields by the end of next week (June 6-10). Traps in MB and the Peace River region should be put out one (Manitoba) or two (Peace River region) weeks later.

Figure 1. Predicted bertha armyworm (*Mamestra configurata*) pupal development (%) across the Canadian prairies as of May 29, 2022.

Flea Beetles Setting Their Sights on Canola

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.

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

A few key links to aid in-field scouting include:

• PPMN’s Weekly Update from May 2021 (Wk 02)
• Biological and pest management information posted by Saskatchewan Agriculture
• Biological and pest management information posted by Manitoba Agriculture and Resource Development
• The Canola Council of Canada’s Flea beetle pages in the Canola Encyclopedia
• Flea beetle pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (Philip et al. 2018) available as an English-enhanced or French-enhanced version.

Predicted diamondback moth development

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. The model, based on climate data, indicates most DBM populations should be in the third generation (Fig. 1). Model simulations to August 8, 2021, predict an additional generation for the current growing season PLUS a third and fourth generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (*Plutella xylostella*) expected to occur across the Canadian prairies **as of August 8 (based on climate normals data)**.

Figure 2. Predicted number of non-migrant generations of diamondback moth (*Plutella xylostell*a) expected to occur across the Canadian prairies **as of August 8, 202**1.

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 3) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. 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” (accessible in either English-enhanced or French-enhanced versions).

Predicted diamondback moth development

Model simulations to August 1, 2021, indicate that the third and fourth generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 1). Compared to long-term average data (climate normal) sufficient heat units have accumulated to produce a predicted an additional generation for the current growing season (Fig. 2).

Figure 2. Long-term average predicted number of non-migrant generations of diamondback moth (*Plutella xylostella*) expected to occur across the Canadian prairies **as of August 1 (based on climate normals data)**.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. 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” (accessible in either English-enhanced or French-enhanced versions).

Predicted diamondback moth development

Diamondback moths (DBM; Plutella xylostella) 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 U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season. Diamondback moth was the Insect of the Week for Wk10!

Model simulations to July 11, 2021, indicate that the second generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 1). A third generation is predicted for southern Manitoba. Based on climate normal inputs, development is well ahead of long-term average values (Figure 2). Based on current weather, the mean number of generations that have occurred is 2.1 compared to model runs, based on climate normals, predict that the number of generations should be 1.4.

Figure 2. Long-term average predicted number of non-migrant generations of diamondback moth *(Plutella xylostella*) expected to have occurred across the Canadian prairies as of July 13 (based on climate normals data).

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. 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” (accessible in either English-enhanced or French-enhanced versions).

Bertha armyworm

Provincial insect pest monitoring networks in Manitoba, Saskatchewan and Alberta are now compiling cumulative counts of adults intercepted from the pheromone-baited green unitraps deployed in fields across the prairies. Review the Provincial Insect Pest Report Links to find summaries or link to the latest bertha armyworm moth counts by clicking the appropriate province’s reporting info for Manitoba, Saskatchewan or Alberta. So far, interception counts remain mainly in the “low risk” categories across the Canadian prairies. Review the 2020 pheromone trapping cumulative moth counts here to identify potential high risk areas to target for scouting for larvae now!

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting. Use the images below (Fig. 1) to help identify the various stages. Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm!

This image has an empty alt attribute; its file name is 2019_PPMN-Protocol_BAW_LifeStages_Williams.png — **Figure 6**. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

Midges in canola

The Insect of the Week features Swede midge and the canola flower midge as doppelganger pests this week!

Two species of midges (Diptera: Cecidmyiidae) are known to infest canola in Canada. Since 2000, swede midge (Contarinia nasturtii) has been established in southern Ontario with serious levels of damage observed in several species of Brassicaceae, including canola by 2003. Swede midge is also established in Quebec, Nova Scotia, and Prince Edward Island. Across the prairie region of Canada, a separate canola flower midge (Contarinia brassicola Sinclair) was identified initially as larvae feeding within the developing flower that caused the formation of a “pop-bottle”-shaped gall (Fig. 1). To date, this is the only damage associated with the canola flower midge, and it has been minimal across the prairies.

Figure. 1. “Pop-bottle”-shaped galls created by the canola flower midge.
(c) 2016 Boyd Mori, AAFC

Because of the serious threat that swede midge poses to canola production, it is vital that monitoring for swede midge continues across the Prairies. Monitoring is underway for 2021.

Tips for scouting canola for midges:
• Watch for unusual plant structures and plant discolourations then follow-up by closely scrutinizing the plant for larvae.
• The growing tip may become distorted and produce several growing tips or none at all, young leaves may become swollen, crinkled or crumpled and brown scarring caused by larval feeding may be seen on the leaf petioles and stems.
• Flowers may fail to open.
• Young plants that show unusual growth habits should be examined carefully for damage and larvae; especially if the sticky liners have many flies resembling midges (swede midges are about the size of orange blossom wheat midge but are not orange).
• Larvae can be seen with a hand lens.

Access more information about midges in canola via these links:
• Swede midge and canola flower midge: Doppelganger pests (2021; Wk 11)
• New canola flower midge (2018; Wk 11)
• Natural enemies of the canola flower midge (2018; WK 12)
• Ontario’s swede midge fact sheet produced by Baute et al. 2016.
• Canola Council of Canada’s Canola Encyclopedia – Swede midge

Predicted diamondback moth development

Model simulations to July 4, 2021, indicate that the second generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 1). Across the prairies, development, as of July 4, 2021, is well ahead of long-term average values (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (*Plutella xylostella*) that are expected to have occurred across the Canadian prairies as of July 4, 2021.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. 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” (accessible in either English-enhanced or French-enhanced versions).

Predicted bertha armyworm development

Model simulations to June 27, 2021 indicate that development of bertha armyworm (BAW) (Mamestra configurata) populations is transitioning to egg and larval stages. Model simulations indicate that BAW oviposition is occurring across most of the prairies with occurrence of larvae across southern regions of all three provinces (Figs. 1 and 2).

Figure 1. Predicted percent of bertha armyworm (*Mamestra configurata*) population that is in the egg stage (% of population) across the Canadian prairies as of June 27, 2021.

Figure 2. Predicted percent of bertha armyworm (*Mamestra configurata*) population that is in the larval stage (% of population) across the Canadian prairies as of June 27, 2021.

BAW populations in southern Manitoba are predicted to be predominantly in the larval stage by early July whereas BAW populations near Grande Prairie will be in the adult and egg stages. Model projections to July 13 predict that development near Brandon will be more advanced than development near Lacombe (Figs. 3 and 4). Over the next few days adult populations should be declining in southern Manitoba. In central Alberta adults should continue to lay eggs over the next 10 days. Above average temperatures will result in rapid development of larval populations.

Figure 3. Predicted development of bertha armyworm (*Mamestra configurata*) populations near Brandon, Manitoba as of June 27, 2021 (projected to July 13, 2021).

Figure 4. Predicted development of bertha armyworm (*Mamestra configurata*) populations near Lacombe, Alberta **as of June 27, 2021 (projected to July 13, 2021).**

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting. Use the images below (Fig. 6) to help identify the various stages. Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm!

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

Predicted diamondback moth development

Model simulations to June 27, 2021, indicate that the first generation of non-migrant adults are currently emerging across the Canadian prairies and that the start of the second generation is occurring in southern Manitoba and southeastern Saskatchewan (Figure 1).

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. 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” (accessible in either English-enhanced or French-enhanced versions).

Predicted bertha armyworm development

Model simulations to June 20, 2021, indicate that the development of bertha armyworm (BAW) (Mamestra configurata) pupae are nearly complete. Other than the Peace River region, BAW adults should now be active across the prairies (Fig. 1). Model simulations indicate that BAW oviposition has begun across southern areas of Manitoba, Saskatchewan and localized areas in Alberta (Fig. 2).

Figure 1. Predicted percent of bertha armyworm (*Mamestra configurata*) population that is in the adult stage (% of population) across the Canadian prairies **as of June 20, 2021**.

Figure 2. Predicted percent of bertha armyworm (*Mamestra configurata*) population that is in the egg stage (% of population) across the Canadian prairies as of June 20, 2021.

Model projections to July 6 predict that development near Brandon will be more advanced than development near Grande Prairie (Figs. 3 and 4). BAW populations in southern Manitoba are predicted to be predominantly in the larval stage by early July whereas BAW populations near Grande Prairie will be in the adult and egg stages.

Figure 3. Predicted development of bertha armyworm (*Mamestra configurata*) populations near Brandon, Manitoba **as of June 20, 2021 (projected to July 6, 2021)**.

Figure 4. Predicted development of bertha armyworm (*Mamestra configurata*) populations near Grande Prairie, Alberta as of June 20, 2021 (projected to July 6, 2021).

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

Predicted diamondback moth development

Diamondback moths (DBM) (Plutella xylostella) 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 U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season.

Model simulations to June 20, 2021, indicate that the first generation of non-migrant adults are currently emerging across the Canadian prairies and that the start of the second generation is occurring in southern Manitoba (Fig. 1).

So far, Manitoba, Saskatchewan, Alberta and the BC Peace are all reporting relatively low numbers of intercepted DBM in pheromone traps (read provincial insect pest report links) despite the fact that favourable wind trajectories have passed over the Canadian prairies from southern regions of North America (review wind trajectory reports for 2021). Even so, once DBM are present in an area, it is important to monitor individual canola fields for larvae. Warm growing conditions can quickly translate into multiple generations in a very short time so use the following photos to help identify larvae (Fig. 2), pupae (Fig. 3), or adults (Fig. 4)!

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m² (approximately 2-3 larvae per plant). Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. 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” (accessible in either English-enhanced or French-enhanced versions).

Cabbage seedpod weevil monitoring

Monitoring is already underway for cabbage seedpod weevil (Ceutorhynchus obstrictus; CSPW) in southern areas of the prairies – it’s the Insect of the Week for Wk08! There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo). Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches.

Monitoring:

Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved24Jun2021).

Lygus bug monitoring

Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.

Scouting tips to keep in mind: Begin monitoring canola when it bolts and continue until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.

Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs. In fact, sampling is most accurate when repeated at a total of 15 spots within the field. Samples can be taken along or near the field margins. Calculate the cumulative total number of lygus bugs and then consult the sequential sampling chart (Figure 3).

**Figure 3**. Sequential sampling for lygus bugs at late flowering stage in canola.

If the total number is below the lower threshold line (Fig. 3), no treatment is needed. If the total is below the upper threshold line, take more samples. If the total is on or above the upper threshold line, calculate the average number of lygus bugs per 10-sweep sample and consult the economic threshold tables (Tables 1 and 2).

The economic threshold for lygus bugs in canola covers the end of the flowering (Table 1) and the early pod ripening stages (Table 2). Once the seeds have ripened to yellow or brown, the cost of controlling lygus bugs may exceed the damage they will cause prior to harvest, so insecticide application is not warranted. Consider the estimated cost of spraying and expected return prior to making a decision to treat a crop.

Remember that insecticide applications at bud stage in canola have not been proven to result in an economic benefit in production. The exception to this is in the Peace River region where early, dry springs and unusually high densities of lygus bug adults can occasionally occur at bud stage. In this situation, high numbers of lygus bugs feeding on moisture-stressed canola at bud stage is suspected to result in delay of flowering so producers in that region must monitor in fields that fail to flower as expected.

How to tell them apart: The 2019 Insect of the Week’s doppelganger for Wk 15 was lygus bug versus the alfalfa plant bug while Wk 16 featured lygus bug nymphs vs. aphids! Both posts include tips to to discern the difference between when doing in-field scouting!

Predicted diamondback moth development

Diamondback moths (DBM; Plutella xylostella) 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 U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season. Model simulations to June 13, 2021 (using a biofix date of May 15, 2021), indicate that the first generation of non-migrant adults are currently emerging across the Canadian prairies (Fig. 1).

Fig. 1 Predicted number of **non-migrant generations** of diamondback moth (*Plutella xylostella*) expected to have occurred across the Canadian prairies **as of June 13, 2021**.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. 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” (accessible in either English-enhanced or French-enhanced versions).

Predicted bertha armyworm development

Model simulations to June 13, 2021, indicate that bertha armyworm (BAW) (Mamestra configurata) pupal development is greater than 75% (Fig. 1). Populations are predominantly in the pupal stage (Fig. 2).

Figure 1. Predicted bertha armyworm (*Mamestra configurata*) **pupal development** (%) across the Canadian prairies as of June 13, 2021.

Figure 2. Predicted percent of bertha armyworm (*Mamestra configurata*) **population that is in the pupal stage** (% of population) across the Canadian prairies **as of June 13, 2021**.

Model simulations indicate that BAW adult emergence has begun across southern areas of Manitoba and Saskatchewan (Fig. 3). Based on pupal development, adult emergence should occur across most of the prairies over the next few days.

Figure 3. Predicted percent of bertha armyworm (*Mamestra configurata*) population that is in the adult stage (% of population) across the Canadian prairies as of June 13, 2021.

Model projections to June 30 predict that development near Winnipeg is more advanced than at Lacombe (Figs. 4 and 5). The model predicts that oviposition has begun near Winnipeg and that egg hatch will begin next week in fields.

Figure 4. Predicted development of bertha armyworm (*Mamestra configurata*) populations near Winnipeg, Manitoba **as of June 13, 2021 (projected to June 29, 2021**).

Figure 5. Predicted development of bertha armyworm (*Mamestra configurata*) populations near Lacombe, Alberta **as of June 13, 2021 (projected to June 29, 2021**).

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting. Use the images below (Fig. 6) to learn to identify the various stages. Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm!

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

Predicted bertha armyworm development

Model simulations to June 6, 2021, indicate that bertha armyworm (BAW) (Mamestra configurata) pupal development ranges from 60-90 % across the prairies (Fig. 1). BAW traps should be placed in fields when pupal development exceeds 80 %. Table 1 provides guidelines to determine when traps should be deployed. Based on weather data up to June 6, 2021, BAW adults should begin to emerge by mid to late June.

Figure 1. Predicted bertha armyworm *(Mamestra configurata*) pupal development across the Canadian prairies as of June 6, 2021.

Model projections to June 30 predict that development near Winnipeg will be more advanced than at Lacombe (Figs. 2 and 3, respectively). The model predicts that egg hatch will begin in mid-June near Winnipeg.

Figure 2. Predicted development of bertha armyworm (*Mamestra configurata*) populations near Winnipeg, Manitoba **as of June 6, 2021 (projected to June 30, 2021)**.

Figure 3. Predicted development of bertha armyworm (*Mamestra configurata*) populations near Lacombe, Alberta **as of June 6, 2021 (projected to June 30, 2021)**.

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

Alert: Bertha armyworm development

Model simulations to May 30, 2021, indicate that BAW pupal development is 45-60 % complete across the prairies (Fig. 1). Recent warm conditions in Alberta and southern Manitoba have resulted in the rapid development of BAW pupae (Fig. 2 C). The weather forecast for this week suggests that above-normal temperatures will occur. This could result in faster development of BAW pupae. BAW traps should be placed in fields when pupal development is approximately 80 %.

Figure 1. Predicted bertha armyworm (*Mamestra configurata*) pupal development across the Canadian prairies **as of May 30, 2021**.

IMPORTANT: Table 1 provides estimates for when the pheromone-baited green unitrap should be deployed. Based on weather conditions up to May 30, 2021, and model output, BAW adults (Fig. 2 D) may begin to emerge by mid to late June. Typically, moths emerge over an ~6 week period so cumulative counts of moths intercepted in these green unitraps provides insight into anticipated risk and prioritization for in-field scouting of the damaging larval stages later this summer.

**Figure** 2. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm.
Photos: Jonathon Williams (AAFC-Saskatoon).

Model projections to June 30 predict that development near Regina (Fig. 3) will be more advanced than at Grande Prairie (Fig. 4). The model predicts that egg hatch will begin in late June near Regina.

Figure 3. Predicted development of bertha armyworm (*Mamestra configurata*) populations near Regina, Saskatchewan, as of May 30, 2021 (projected to June 30, 2021).

Figure 4. Predicted development of bertha armyworm (Mamestra configurata) populations near Grande Prairie, Alberta **as of May 30, 2021 (projected to June 30, 2021)**.

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

Flea beetles

Two species, Phyllotreta striolata and P. cruciferae, are the most chronic and economically important flea beetle pests of cruciferous crops in western Canada. Bioclimate simulation models for the two flea beetle species were developed to assess how climatic factors influence shifts in their geographic distribution and relative abundance. Economic risk was associated with populations in the orange and red zones (Figs. 1-4). It is crucial to note that the following information is NOT based on flea beetle densites BUT IS INSTEAD reflecting the suitability of environmental factors for P. striolata and P. cruciferae to prosper in highlighted areas of the following maps.

This spring has been approximately 1 °C cooler than normal. Recent rain (May 23-24) has resulted in precipitation amounts that are normal to above normal (30-day total) across Alberta and Saskatchewan. Simulations were run to determine how the two flea beetle species might respond to cooler, wetter conditions (compared to average growing seasons). Based on average temperature and precipitation (based on long term climate normals) risk associated with P. cruciferae is most prevalent across the southern prairies and risk related to P. striolata tends to be greatest across the Parkland and Peace River regions (Figs. 1 and 2).

Figure 1. Predicted risk for P. cruciferae, for model simulations based on long term climate normals. Red and orange regions may
be associated with economic crop losses.

Figure 2. Predicted risk for *P. striolata*, for model simulations based on long term climate normals. Red and orange regions may
be associated with economic crop losses.

For both species, cooler/wetter conditions generally could result in reduced risk and southward shifts in distribution (Figs. 3 and 4). Cooler and wetter than average growing seasons were predicted to have less negative impact on P. striolata than P. cruciferae. For example, Peace River populations of P. striolata are predicted to present reduced risk with cooler, wetter conditions (compared to average climate). Under similar conditions, P. cruciferae was predicted to have significantly reduced risk in the Peace River region. Wetter than average conditions in Manitoba may result in reduced risk from P. cruciferae and P. striolata. Olfert et al. (2017) reported that both species were more sensitive to temperature than moisture. Potential risk related to warmer temperatures was greater for P. cruciferae than P. striolata. Producers should monitor flea beetle species composition, crop stage and weather to assess potential flea beetle risk to cruciferous crops.

Figure 3. Predicted risk for *P. cruciferae*, for model simulations based on conditions that are cooler and wetter than current climate. Red and orange regions may be associated with economic crop losses.

Figure 4. Predicted risk for *P. striolata*, for model simulations based on conditions that are cooler and wetter than current climate. Red and orange regions may be associated with economic crop losses.

If flea beetle densities are high, seedling damage levels can advance quickly – even within the same day! The cotyledon stage of canola is vulnerable to flea beetle feeding. Review photos of flea beetle feeding damage posted earlier in the Weekly Update (Wk 02 – May 14, 2021) to help assess percent defoliated and to apply the action threshold of 25 % leaf area of cotyledons consumed plus flea beetles were the Insect of the Week (Wk 02 – May 10)!

Access biological and pest management information posted by Alberta Agriculture and Forestry, Saskatchewan Agriculture, or Manitoba Agriculture and Resource Development, or the Canola Council of Canada’s Canola Encyclopedia. Refer to the flea beetle page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (Philip et al. 2018) as an English-enhanced or French-enhanced version.

Bertha armyworm development

Model simulations to May 23, 2021, indicate that overwintered BAW pupal development (Fig. 1, C) varies across the prairies. Development is predicted to be greatest across the southern prairies (Fig. 2). Based on current development, adult emergence is projected to occur in mid-June.

**Figure** 1. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm.
Photos: Jonathon Williams (AAFC-Saskatoon).

Figure 2. Predicted bertha armyworm (*Mamestra configurata*) pupal development across the Canadian prairies as of May 23, 2021.

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

Scouting charts for canola and flax

Reminder – Field scouting is critical – it enables the identification of potential risks to crops. Accurate identification of insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions.

We offer TWO generalized insect pest scouting charts to aid in-field scouting on the Canadian prairies:

1. CANOLA INSECT SCOUTING CHART (click chart to access downloadable PDF copy)

2. FLAX INSECT SCOUTING CHART(click chart to access downloadable PDF copy)

These charts feature hyperlinks directing growers to downloadable PDF pages with photos within the “Field crop and forage pests and their natural enemies in western Canada: Identification and management field guide“.

Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species.

Flea beetles

Newly emerging Brassicaceae but especially canola is attractive to overwintered flea beetles that emerge and become active early in the spring. As canola seedlings emerge, in-field scouting becomes crucial! If flea beetle densities are high, seedling damage levels can advance quickly – even within the same day! The cotyledon stage of canola is vulnerable to flea beetle feeding. Be sure to check out the Insect of the Week – Week 2 featured flea beetles!

Several species of flea beetles are present across North America. Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem (Fig. 1). Two species, Phyllotreta striolata (Fig. 1) and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.

Figure 1. Flea beetle feeding damage (L) and striped flea beetle (R).

The Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding.

Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (Figs. 2 and 3; copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!

Figure 2. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).

Figure 3. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).

Two other favourite flea beetle resources relevant to field crop protection include:

Those armed with a stereomicroscope who are keen to monitor flea beetle species may wish to bookmark the “Common flea beetles of North Dakota” (Fauske 2003) which an excellent online resource and includes many of the commonly observed species of flea beetles also present across the Canadian prairies.

Soroka, J., Grenkow, L., Otani, J., Gavloski, J., & Olfert, O. (2018). Flea beetle (Coleoptera: Chrysomelidae) species in canola (Brassicaceae) on the northern Great Plains of North America. The Canadian Entomologist, 150(1), 100-115. doi:10.4039/tce.2017.60

Flea beetles active already

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.

More information about these pests (lifecycle, damage, control options, etc.) and others is available in the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide. (en français : Guide d’identification des ravageurs des grandes cultures et des cultures fourragères et de leurs ennemis naturels et mesures de lutte applicables à l’Ouest canadien)

Crucifer flea bettle — Crucifer flea beetle (AAFC)

Predicted diamondback moth development

The Diamondback moth (DBM) model was run with a biofix of May 15, 2020. DBM densities generally increase with increasing numbers of generations. Figure 1 represents the model output for the 2020 growing season (as of August 17, 2020). The number of generations varies from two in western Alberta to four in southeastern Saskatchewan and most of Manitoba (Fig. 1). Next, the model was run with climate normal data to compare the 2020 growing season with an ‘average’ growing season (Fig. 2). The second map (climate normal) indicates that an average growing season results in two to three generations, with a fourth generation predicted to occur near Winnipeg (Fig. 2). These results indicate that there was an elevated DBM risk in 2020.

**Figure 1**. Using a biofix date of May 15, 2020, the projected number of diamondback moth (*Plutella xylostella*) generations across the Canadian prairies as of August 17, 2020.

**Figure 2**. Using a biofix date of May 15, 2020, the projected number of diamondback moth (*Plutella xylostella*) generations across the Canadian prairies as of August 17, 2020, using climate normal data.

Monitoring to apply the economic threshold: Remove the plants in an area measuring 0.1 m² (about 12″ square). Beat them on to a clean surface and count the number of larvae (Fig. 3) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

This image has an empty alt attribute; its file name is DBM_Larva_AAFC.jpg — **Figure 3**. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

Biological and monitoring information for DBM is posted by Manitoba Agriculture, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network.

More information about Diamondback moths can be found by accessing the pages from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide“. View ONLY the Diamondback moth page but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

Preparing and protecting grains for market

A few helpful tools to keep at your finger tips:

A number of important resources are available at Keep It Clean to help prepare and protect grains for market. Learn more about preparing canola, cereals and pulses! They also have tools to manage pre-harvest intervals including a spray to swath calculator and describe the importance of avoiding malathion in bins storing canola.

Download searchable PDFs of 2020 Crop Production Guides for Alberta, Saskatchewan and Manitoba.

The Canadian Grain Commission has information to help you manage stored grain. Read tips to prepare your bins to prevent insect infestations. If there are insects in your grain, use their online diagnostic tools to help identify the problem species. If pest species are confirmed, there are control options – read more to make the right choice for your grain storage system and your specific grain.

Bertha armyworm

Weekly Pheromone-baited Trapping Results – Click each province name to access moth reporting numbers observed in Alberta, Saskatchewan and Manitoba (as they become available). Check these sites to assess cumulative counts and relative risk in your geographic region but remember in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. For convenience, screen shots of the above maps or data have been placed below for Alberta, Saskatchewan, and Manitoba.

Monitoring:

Larval sampling should commence once the adult moths are noted.
Sample at least three locations, a minimum of 50 m apart.
At each location, mark an area of 1 m2 and beat the plants growing within that area to dislodge the larvae.
Count them and compare the average against the values in the economic threshold table below:

Scouting tips:
● Some bertha armyworm larvae remain green or pale brown throughout their larval life.
● Large larvae may drop off the plants and curl up when disturbed, a defensive behavior typical of cutworms and armyworms.
● Young larvae chew irregular holes in leaves, but normally cause little damage. The fifth and sixth instar stages cause the most damage by defoliation and seed pod consumption. Crop losses due to pod feeding will be most severe if there are few leaves.
● Larvae eat the outer green layer of the stems and pods exposing the white tissue.
● At maturity, in late summer or early fall, larvae burrow into the ground and form pupae.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting. Use the images below (Fig. 1) to help identify the economically important larvae. Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm!

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.