Tag: Wheat

Predicted wheat midge development

The emergence of wheat midge (Sitodiplosis mosellana) needs to be synchronized with the development of wheat heads for successful larval development. One factor that determines the timing of adult wheat midge emergence is spring precipitation. Cumulative rainfall between 25-30 mm in May and June is required for overwintered larval cocoons to complete larval and pupal development in the spring. When cumulative rainfall is below 25-30 mm in May and June, the completion of larval development may be delayed or postponed to future growing seasons, resulting in delayed or erratic adult wheat midge emergence in late June and July.

Cumulative rainfall (May 1-June 29, 2025) across the majority of the Canadian Prairies now exceeds the threshold (30 mm) required to terminate larval diapause.

The model indicates that, where wheat midge populations are present, larvae are beginning to pupate in larger numbers (Fig. 1). Model output suggests that pupae numbers should be highest in the southwest corner of Saskatchewan and around Brandon in Manitoba (Fig. 1).

**Figure 1.** Percent of wheat midge larval population (*Sitodiplosis mosellana*) predicted to be in the pupal stage across western Canada, ***as of June 29, 2025***.

Please refer to the historical wheat midge survey maps and particularly the 2024 results. Historical survey information paired with updated predictive model outputs help identify areas at risk of wheat midge damage in 2025.

In-Field Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis. In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 3). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

**Figure 3**. Wheat midge (*Sitodiplosis mosellana*) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.

**Figure 4**. *Macroglenes penetrans*, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. Photo: AAFC-Beav-S. Dufton.

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 4), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Economic Thresholds for Wheat Midge:
a) To maintain optimum No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) To maintain yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and larval damage.

Wheat midge was featured as the Insect of the Week in 2023 (for Wk08). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting! Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12). Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Ministry of Agriculture or Alberta Agriculture & Irrigation). Alberta Agriculture & Irrigation has a YouTube video describing in-field monitoring for wheat midge. The Prairie Pest Monitoring Network’s wheat midge monitoring protocol is also available.

Additional information can be accessed by reviewing the Wheat midge pages extracted from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.

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 Wk15 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, faba beans, and lentils)
• 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.

Additionally, 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) which 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) presently 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)

Wheat head armyworm

Wheat head armyworm (Lepidoptera: Noctuidae): Dargida diffusa (Walker, 1856) feeds on several grassy-type species including wheat, rye, oats, barley, wild oats, native and forage grasses (although timothy is preferred). Wheat head armyworm overwinter within earthen cells as pupae. Each growing season, there are two generations of adults produced. This means both a spring and summer larval generation occur, however, the first generation can cause damage early in the growing season in wheat and some grasses (Fig. 1) although infestations are very sporadic and rarely reach densities requiring control.

Adult moths are 30-38 mm in wing span, are yellowish-brown, but have a chocolate-brown stripe running down the length of each forewing. Larvae have a pale brown head capsule, grow to ~25 mm long, and are bright green or tan with lateral white stripes that help camouflage them on awns (Fig. 2). The previous alternate scientific name for this species was Faronta diffusa. Wheat head armyworm are surprisingly difficult to spot in situ and are sometimes initially detected in sweep-nets (Fig. 3).

**Figure 2.** Examples of three colour morphs of wheat head armyworm (Noctuidae: *Dargida diffusa*) on cereals growing in the Peace River region in 2024; note consistent stripe patterning but larval body colour can range from bright green to tan. Photos kindly shared by: **B. DeSmet**, Dirt Road Agronomy.

**Figure 3.** Green and tan colour morphs of wheat head armyworm (Noctuidae: *Dargida diffusa*) retrieved in sweep-net sample on August 10, 2020, in wheat growing near Magrath AB. Photo kindly shared by: **A. Voss**, @Voss_Ag

Infestations are very sporadic. There is no nominal or economic threshold for this species in any of the field crop species listed above. Beneficial insects like the parasitoid wasps within the genus Cotesia will attack wheat head armyworm larvae and, shortly after erupting from the larval host, will form clusters of white cocoons (Fig. 4) that eventually yield new parasitoid wasps which subsequently seek out and attack other armyworms.

**Figure 4.** *Cotesia* cocoons spun on wheat awns that presumably erupted from immobile larva of wheat head armyworm (Noctuidae: *Dargida diffusa*) that has numerous lateral exit wounds. Photo taken August 10, 2020, near Magrath AB and kindly shared by:**A. Voss**, @Voss_Ag

Distribution records for D. diffusa can be reviewed on the Butterflies of North America website although these records would greatly benefit with sightings in western Canada because the species is established in Alberta (central and in the south east of the Peace River region), in Saskatchewan, and Manitoba.

Biological and monitoring information for this insect pest species is accessible as a wheat head armyworm page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018). The entire guide is accessible as a free downloadable PDF in either English or French on our Field Guides page.

European Skipper

The European skipper (Hesperiidae: Thymelicus lineola) is a diurnal, bright orange butterfly (Fig. 1). The predominantly green defoliating larvae can cause economic levels of damage in timothy. The larvae also feed on other species of grasses and winter wheat.

There is one generation per year of European skipper but butterfly oviposition or egg laying largely dictates where damage occurs the following summer. Host plants include timothy (Phleum pretense), cocksfoot (Dactylis glomerata), couch or quack grass (Agrophyron repens), perennial ryegrass (Lolium perenne), meadow fescue (Festuca pratensis), orchardgrass (Dactylis glomerata).

Early in July, butterflies feed on nectar, mate, and lay eggs. Females lay vertical rows or “strings” of groups of ~30 eggs on the inside of grass leaf sheaths, seed heads or on the stem of a host plant. By late July, larvae develop within the eggs yet they remain safely enclosed to overwinter inside the egg shell. Eggs can be transferred in both hay and seed as seed cleaning will not remove all eggs. Early the following May, the overwintered larvae emerge from the shell, crawling up growing grass blades to feed. Five larval instar stages cause damage by defoliation of the upper leaves of timothy.

Larvae are leaf-tyers that spin and attach silk ties across the outer edges of leaves to pull them together (Figs. 2-5). The silk ties hold the leaf in a tight furl enclosing the larva within a leafy tube then it moves up and down the tube to feed. The tying behaviour and camouflaged green body (marked longitudinally with two white lines) make larvae hard to locate when scouting. Even larger larvae with their brown head capsules are surprisingly difficult to locate because the larva will lie lengthwise, along the base of the leaf fold yet the larva remains very still until touched. When high densities of European skipper larvae are present, leaf tying goes out the window and larvae feed in more exposed areas, often amidst rapidly disappearing foliage.

Adult wingspans range from 19-26 mm but they have bright brassy orange wings with narrow black borders and hindwing undersides that are pale orange and greyish. Nectar sources for adults include orange hawkweed, thistles, oxeye daisy, fleabane, white clover, red clover, common milkweed.The typical flight season extends from early June to mid-July but will vary regionally with southern parts of the Canadian prairies starting earlier than more northern regions.

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

Cultural control strategies for European skipper include separating timothy from nectar sources to avoid attracting adults which will mate then oviposit in the same field. Another strategy is the removal of cut grass or bales.

In terms of chemical control, an action threshold of six or more larvae per 30 cm x 30 cm area is recommended to mitigate losses but emphasis should be placed on scouting and managing early instar larvae. If the need arises, chemical control in timothy involves using a higher water volume (e.g., 300 L H₂O/ha) to adequately cover the thicker canopy.

**Figure 2**. Early instar larva feeding along edge of timothy leaf. Photo: A. Jorgensen, AAFC-Beaverlodge.

Figure 3. Larva resting in fold of timothy leaf formed by silken tie. Photo: K. Pivnick. AAFC-Saskatoon.

Figure 4. Larval feeding damage and silken ties on timothy leaf. Photo: K. Pivnick, AAFC-Saskatoon).

Figure 5. *In situ* camouflaged larvae and feeding damage in timothy. Photo: S. Barkley.

The European skipper was introduced to North America at least a century ago and has moved west and north in its distribution across western Canada even though its area of origin is recognized as Eurasia and northwestern Africa. The initial report of European skipper in Canada is from 1910 and cites it being imported on contaminated timothy seed near London, Ontario.

Distribution records for T. lineola can be reviewed on the Butterflies of North America website. In western Canada, T. lineola established in parts of Saskatchewan by 2006. In 2008, butterflies were collected near Valleyview, Alberta (Otani, pers.comm.), and in 2015 larvae were observed feeding in the flag leaves of winter wheat near Mayerthorpe, Alberta (2015 Meers, pers. comm.). Specimens confirmed as T. lineola were collected in 2016 near Valleyview, Donnelly, and High Prairie, Alberta (2017 Otani and Schmidt, pers. comm.) with additional specimens confirmed from Baldonnel and Clayhurst, British Columbia in 2021 (2021 Otani and Schmidt, pers. comm.).

The European skipper was the Insect of the Week in 2022 (Wk10).

Cereal leaf beetle

The cereal leaf beetle (Chrysomelidae: Oulema melanopus) has a broad host range. Wheat is the preferred host, but adults and larvae also feed on leaf tissue of oats, barley, corn, rye, triticale, reed canarygrass, ryegrass, fescue, wild oats, millet and other grasses. Yield quality and quantity is decreased, if the flag leaf is stripped. Fun fact: Cereal leaf beetle larvae carry their own fecal waste above their body to help protect themselves from predators.

Fortunately, the parasitoid wasp, Tetrastichus julis Walker (Hymenoptera: Eulophidae), is an important natural enemy of cereal leaf beetle larvae. Learn more about this beneficial insect species featured in Week 9 of 2023’s Insect of the Week!

Cereal Leaf Beetle Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing covers (Fig. 1). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelterbelts, deciduous and conifer forests. They emerge in the spring once temperatures reach 10-15 ºC and the adults are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.

**Figure 1**. Adult *Oulema melanopus* measure 4.4-5.5 mm long (Photo: M. Dolinski).

Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the midvein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 2). When the larva completes its growth, it drops to the ground and pupates in the soil.

**Figure 2**. Larval stage of *Oulema melanopus* with characteristic feeding damage visible on leaf (Photo: M. Dolinski).

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

Access scouting tips for cereal leaf beetle or find more detailed information by accessing the Oulema melanopus page from 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.

Wheat head armyworm

Wheat midge

The emergence of adult wheat midge (Sitodiplosis mosellana) needs to be synchronized with the development of wheat heads for successful larval development. One factor that determines the timing of adult wheat midge emergence is spring precipitation. Cumulative rainfall between 25-30 mm in May and June is required for overwintered larval cocoons to complete larval and pupal development in the spring. When cumulative rainfall is below 25-30 mm in May and June, the completion of larval development may be delayed or postponed to future growing seasons, resulting in delayed or erratic adult wheat midge emergence in late June and July.

Cumulative rain (May 1-June 15) across the majority of Alberta and Manitoba now exceeds the threshold (30 mm) required to terminate larval diapause (Fig. 1). Several areas including surrounding Saskatoon (Rosetown, North Battleford, Elbow) and west of Lethbridge (Medicine Hat, Maple Creek, Alsask) have not reached this threshold. However, this is likely to change if those areas receive 10 mm or more of rainfall over the next week.

**Figure 1**. Areas in western Canada where cumulative rainfall from May 1 to June 15, 2025 is equal to or greater than 30 mm, which is the threshold required to promote movement of wheat midge (*Sitodiplosis mosellana*) larvae to the soil surface where they will pupate.

Based on model readings, where wheat midge populations are present, larvae have begun to move to the soil surface (Fig. 2). Where wheat midge populations exist, the proportion of the larval population at the soil surface and ready to pupate is highest in eastern AB, southeastern SK, and southwestern MB. Model output suggests that pupation should start to occur next week.

**Figure 2**. Percent of wheat midge larval population (*Sitodiplosis mosellana*) that has moved to the soil surface across western Canada, as of June 15, 2025.

Cereal leaf beetle

Cereal Leaf Beetle Lifecycle and Damage:

Cereal leaf beetle

Cereal Leaf Beetle Lifecycle and Damage:

Cereal leaf beetle

Cereal Leaf Beetle Lifecycle and Damage:

Cereal leaf beetle

Cereal Leaf Beetle Lifecycle and Damage:

Cutworms

Cutworm scouting spans April to late June across the Canadian prairies! Scout fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look. Plan to follow up by walking these areas either very early or late in the day when some cutworm species (or climbing cutworms) move above-ground to feed. Start to dig below the soil surface (1-5 cm deep) near the base of symptomatic plants and also any healthy plants immediately adjacent to missing rows or wilting or clipped plants. Some cutworms feed while remaining just below the soil surface, clipping then pulling the plant below the soil surface as they munch away! If the plant is well-established (e.g., perennial grass or legume), check within the crown plus in the adjacent soil. The culprits could be cutworms, wireworms, or more!

Important: Several species of cutworms (Lepidoptera: Noctuidae) can be present in fields. They range in colour from shiny opaque, to tan, to brownish-red with chevron patterning. A field guide is available to help growers scout and manage the various species of cutworms that can appear in field crops grown on the Canadian prairies. Cutworm Pest of Crops is available free in either English or French! Download a searchable PDF copy to access helpful diagnostic photos plus a table showing which larvae are active at different points in the growing season!

Other vital resources to scout and manage cutworms include:

● For anyone on the Canadian prairies, Manitoba Agriculture’s Cutworms in Field Crops fact sheet includes suggested nominal thresholds for cutworms in several crops (Table 1). The same fact sheet describes important biological information, and provides great cutworm photos to support in-field scouting!

● For Albertans….. If you find cutworms, please consider using the Alberta Insect Pest Monitoring Network’s “2025 Cutworm Reporting Tool” then view the live 2025 cutworm map updated daily. Review the live map to see where cutworms are appearing then prioritize in-field scouting accordingly.

● Cutworms were featured as 2024’s first Insect of the Week.

This image has an empty alt attribute; its file name is CutwormNominalThresholds_MB-Ag_2024May.png

Text and table extracted from Gavloski, J. 2024. Cutworms in Field Crops. Manitoba Agriculture. Pages 1-6. Available at https://www.gov.mb.ca/agriculture/crops/insects/pubs/cutworms-in-field-crops.pdf (retrieved May 8, 2025).

Cereal leaf beetle

Cereal Leaf Beetle Lifecycle and Damage:

Cereal leaf beetle

Cereal Leaf Beetle Lifecycle and Damage:

Week 17: Invasive Insect Awareness

Invasive insects and other invasive pests can have significant and negative impacts on agroecosystems and increase the cost of crop production. For example, the pea leaf weevil and cabbage seedpod weevil invaded and established in the prairie region in the past 25 years. Both have affected yield and required insecticide application for management.

Managing invasive alien species, including insects, involves: Preparedness, Prevention, Detection, Response and Recovery.

Preparedness, Prevention, and Detection are important steps that can help to keep invasive species from becoming established. Everyone can help to prevent the invasion of insects by following guidelines to avoid the accidental movement or introduction of insects to Canada.

Similarly, everyone can help with early detection of invasive insects. In the Prairie Region, 12 important insect pests to watch out for are included on posters developed by the Canadian Plant Health Council. The poster is also available in French.

This is the last Insect of the Week post of 2024. Thank you for reading the Insect of the Week series this year!

Week 16: Wheat Stem Sawfly

The wheat stem sawfly, Cephus cinctus, is native to western Canada. Its hosts include species of native grasses as well as rye, barley, and winter wheat. It is most economically damaging to spring wheat and durum wheat in western Canada.

**An adult wheat stem sawfly. Picture by Dylan Sjolie, AAFC-Saskatoon.**

Adult wheat stem sawfly do not feed; they live for about 10 days and spend that time mating, dispersing to wheat or durum crops, and laying eggs. Larvae are the damaging stage of the wheat stem sawfly life cycle. Larvae feed on pith inside the wheat stems. Because the larvae feed inside the wheat stems, the damage they cause is not obvious or easy to detect.

By feeding inside the host plant stems, wheat stem sawfly can reduce the quality and quantity of the grain produced by their host. In the late summer, the larvae also cut the stems of their host plant when they prepare to overwinter. The cut stems are susceptible to lodging.

In the fall, cut stems are used to estimate the density of wheat stem sawfly in wheat and durum fields using the protocol available from the Prairie Pest Monitoring Network. The results of the survey conducted in fall 2023 indicated that wheat stem sawfly densities were quite high in southern Alberta and south western Saskatchewan. Historical maps of the results of the wheat stem sawfly survey are also available from the PPMN Risk Maps page.

Additional information about the wheat stem sawfly is available from the Saskatchewan Ministry of Agriculture and from Alberta Agriculture and Irrigation. For more information, wheat stem sawfly was featured as an Insect of the Week in 2023 and is included 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).

Crickets

Two species of crickets of agricultural significance can be found in more southern regions of the Canadian prairies. The Mormon cricket (Anabrus simplex Haldeman) is typically active as an adult from late June to mid-September. Host plants for the nymphs and adults include broad-leafed plants but they will also feed on sagebrush, grasses and small shrubs, as well as wheat, barley, alfalfa, sweet clover, some forages and garden vegetables plus other insects. Fall field crickets (Gryllus pennsylvanicus Burmeister) are normally observed from late July to the end of September. Fall field crickets (nymphs and adults) can feed and affect seed yields in forages grown for seed, cereals, and some small fruits when they occur at high densities, however, fall field cricket adults are predators of grasshopper eggs.

The Mormon cricket was featured as the Insect of the Week back in 2021 and images of the fall field cricket can be viewed online at Bug Guide. Check out the Bug Guide link to the “Singing insects of North America” to learn more about fall field crickets!

Biological and monitoring information for fall field cricket (Gryllus pennsylvanicus Burmeister) and Mormon cricket (Anabrus simplex Haldeman) are described in the cricket 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.

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.

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)

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)

Wheat midge

Important – the accumulated precipitation levels over past 60 days (May 5 to July 3, 2024) were mapped in Figure 1 and ranged from 60 to >250 mm across the prairies, well beyond the 45 mm threshold that facilitates larvae to exit their cocoons to pupate in the soil then emerge. Areas in Figure 1 receiving substantial rainfall this spring need to plan to scout for wheat midge now as adults typically emerge and seek wheat in early July.

**Figure 1**. 60 day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 5 -July 3, 2024.

Remember – the rate of development and timing of adult midge emergence varies at the field level and can only be verified through in-field scouting. Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of wheat midge on plants are carefully compared to the economic thresholds.

Producers opting to grow cultivars susceptible to wheat midge need to be mindful that any historically elevated density of wheat midge occurring over the past one or even possibly six years across the prairies that also has received substantial rainfall since May of 2024, warrants in-field monitoring now. Review the past wheat midge maps here in relation to your fields THEN compare the historical densities to areas of high precipitation in Figure 1.

Albertans… please refer to this week’s Provincial Insect Pest Report Links to link to count reports of wheat midge for 2024.

Cereal leaf beetle

The cereal leaf beetle (Chrysomelidae: Oulema melanopus) has a broad host range. Wheat is the preferred host, but adults and larvae also feed on leaf tissue of oats, barley, corn, rye, triticale, reed canarygrass, ryegrass, fescue, wild oats, millet and other grasses. Yield quality and quantity is decreased, if the flag leaf is stripped. Fortunately, the parasitoid wasp, Tetrastichus julis Walker (Hymenoptera: Eulophidae), is an important natural enemy of cereal leaf beetle larvae. Learn more about this beneficial insect species featured in Week 9 of 2023’s Insect of the Week!

Cereal Leaf Beetle Lifecycle and Damage:

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 1). When the larva completes its growth, it drops to the ground and pupates in the soil.

**Figure 1**. Larval stage of *Oulema melanopus* with characteristic feeding damage visible on leaf (Photo: M. Dolinski).

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing covers (Fig. 2). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelterbelts, deciduous and conifer forests. They emerge in the spring once temperatures reach 10-15 ºC and the adults are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.

**Figure** 2. Adult *Oulema melanopus* measure 4.4-5.5 mm long (Photo: M. Dolinski).

True armyworm

Similar to diamondback moth, the true armyworm, or just armyworm (Mythimna unipuncta or Pseudaletia unipunctata) is a migratory pest in Canada. After arriving from the United States, true armyworm can have two generations of larvae before cool temperatures in the fall stop their development. True armyworm caterpillars feed along leaf margins of their hosts, leaving damage that could be misdiagnosed as grasshopper or bertha armyworm damage. Preferred hosts include native grasses, wheat, rye, corn, oats, and barley. Other hosts can include crucifer vegetables (e.g., cabbage) and alfalfa.

The economic threshold for true armyworm larvae in cereals is 10 larvae/m². If scouting in the evening or at night, beat plants in a 1 m² area and count the dislodged larvae. True armyworm larvae are more likely to be on the ground during the day, so look under leaf litter and other debris around the plants in a 1 m² area and count the larvae. For more information and tips for scouting, refer to the armyworm pages of 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 OR access Manitoba Agriculture’s scouting guide.

Wheat midge

Although the PPMN is unable to model and predict wheat midge development as in previous years, accumulated precipitation levels during May and June provide guidance in terms of in-field scouting. Elliott et al. (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. (2016) ran model simulations to demonstrate how rainfall impacts wheat midge population density. The Olfert et al. (2020) model indicated that dry conditions may result in: (a) Delayed adult emergence and oviposition, and (b) Reduced numbers of adults and eggs.

Albertans… please refer to this week’s Provincial Insect Pest Report Links to link to count reports of wheat midge for 2024.

Cereal leaf beetle

The cereal leaf beetle (Chrysomelidae: Oulema melanopus) has a broad host range. Wheat is the preferred host, but adults and larvae also feed on leaf tissue of oats, barley, corn, rye, triticale, reed canarygrass, ryegrass, fescue, wild oats, millet and other grasses. Yield quality and quantity is decreased, if the flag leaf is stripped. Fortunately, the parasitoid wasp, Tetrastichus julis Walker (Hymenoptera: Eulophidae), is an important natural enemy of cereal leaf beetle larvae. Learn more about this beneficial insect species featured in Week 9 of 2023’s Insect of the Week!

Cereal Leaf Beetle Lifecycle and Damage:

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 1). When the larva completes its growth, it drops to the ground and pupates in the soil.

True armyworm

Phermone traps have been deployed by the Saskatchewan Ministry of Agriculture and Manitoba Agriculture and by their collaborators and volunteers in both provinces to detect the arrival of immigrating true armyworm. In Saskatchewan, true armyworm have been caught by pheromone traps in the northeast and central parts of the province. In Manitoba, true armyworm have been caught in all five regions.

The economic threshold for true armyworm larvae in cereals is 10 larvae/m2. If scouting in the evening or at night, beat plants in a 1 m² area and count the dislodged larvae. True armyworm larvae are more likely to be on the ground during the day, so look under leaf litter and other debris around the plants in a 1 m² area and count the larvae. For more information and tips for scouting, refer to the armyworm pages of 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 OR access Manitoba Agriculture’s scouting guide.

Week 9: Wheat Midge

Wheat midge, Sitodiplosis mosellana, is an important pest of spring wheat, winter wheat, durum wheat and triticale. Spring rye can also experience some damage from wheat midge. Adult wheat midge do not damage their host plant, but do lay eggs that give rise to the damaging larval stage.

Wheat midge larvae feed on the outside of wheat kernels. Larval feeding results in shrunken, shriveled, and/or cracked kernels. Larval feeding can also cause kernel development to be aborted.

Feeding damage caused by larval wheat midge reduces grain yield and the quality of the harvested grains. Grains with wheat midge damage are typically downgraded at the grain elevator.

Wheat midge damage to the kernels is not easy to detect and can go unnoticed. Therefore, scouting for adult wheat midge is necessary to determine if foliar insecticides may be needed to prevent female wheat midge from laying eggs. Scout for adults in the evenings, daily during the susceptible plant stage. Calm evenings are best for scouting. Count the adults on 4-5 wheat heads at 5 locations in the crop to estimate midge per wheat head. Economic thresholds are:

>1 wheat midge per 4-5 wheat heads (to prevent yield loss)
>1 wheat midge per 8-10 wheat heads (to prevent grade reduction)

For more information about wheat midge, please visit the Prairie Pest Monitoring Network’s Risk Maps page to see annual wheat midge survey results, and previous Insect of the Week posts about wheat midge and its parasitoid, Macroglenes penetrans. Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture, and Manitoba Agriculture also have great wheat midge information resources and you can find information about wheat midge in Field Crop and Forage Pests and their Natural Enemies in Western Canada (also available in French).

Wheat midge

Soil moisture conditions in May and June significantly impacts wheat midge emergence. Where wheat midge cocoons are present in soil, the 2024 growing season’s rainfall during May and June will determine if overwintered larvae will terminate diapause then move to the soil surface to pupate. Pupae develop near the soil surface with adults emerging to seek flowering wheat plants.

Although the PPMN is unable to model and predict wheat midge development as in previous years, accumulated precipitation levels during May and June do provide guidance in terms of in-field scouting. Elliott et al. (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. (2016) ran model simulations to demonstrate how rainfall impacts wheat midge population density. The Olfert et al. (2020) model indicated that dry conditions may result in: (a) Delayed adult emergence and oviposition, and (b) Reduced numbers of adults and eggs.

In 2024, the accumulated precipitation levels over past 60 days (April 25 to June 24, 2024) were mapped in Figure 1 and ranged from 45-250 mm across the prairies. Areas in Figure 1 receiving substantial rainfall this spring need to plan to scout for wheat midge now as adults typically emerge and seek wheat in late June and early July. In contrast, midge emergence may be delayed or erratic where rainfall fails to exceed 20-30 mm during May and June.

**Figure 1**. 60 day cumulative rainfall (mm) observed across the Canadian prairies for the period of April 25 -June 24, 2024.

Soil core sampling to assess the densities of larvae were collected across Saskatchewan and Alberta post-harvest in 2023 (Fig. 2). Fields where cultivars that are susceptible to wheat midge were grown were targeted so densities of overwintering larvae (and respective parasitism) could be determined to help estimate risk for 2024. Although the 2023 survey found relatively low densities of wheat midge in most sampled fields, be mindful – wheat midge larval cocoons can survive for several years in the soil, waiting for wet spring conditions.

This means, producers opting to grow cultivars that are susceptible to wheat midge need to be mindful that any historically elevated density of wheat midge occurring over the past one or even possibly six years across the prairies that also has received substantial rainfall since May of 2024, warrants in-field monitoring now. Review the past wheat midge maps here in relation to your fields THEN compare the historical densities to areas of high precipitation in Figure 1.

**Figure 2.** Wheat midge larval cocoon densities in fields planted to wheat in 2023 estimated using soil core sampling performed post-harvest. *Notes: (a) Samples were not collected from non-wheat fields; (b) In southern Alberta, only irrigated fields were sampled south of Highway 1 due to extreme dry conditions.*

In-Field Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 3). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

Cereal leaf beetle

Cereal Leaf Beetle Lifecycle and Damage:

True armyworm

Wheat midge

In 2024, the accumulated precipitation levels over past 30 days (May 11 to June 9, 2024) were mapped in Figure 1 and ranged from 15-135 mm across the prairies. Areas in Figure 1 receiving substantial rainfall this spring need to plan to scout for wheat midge now as adults typically emerge and seek wheat in late June and early July. In contrast, midge emergence may be delayed or erratic where rainfall fails to exceed 20-30 mm during May and June.

**Figure 1**. 30 day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 11-June 9, 2024.

In-Field Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.

Cereal leaf beetle

Cereal Leaf Beetle Lifecycle and Damage:

True armyworm

Cereal leaf beetle

Cereal Leaf Beetle Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing covers (Fig. 3). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelterbelts, deciduous and conifer forests. They emerge in the spring once temperatures reach 10-15 ºC and the adults are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.

**Figure 3**. Adult *Oulema melanopus* measure 4.4-5.5 mm long (Photo: M. Dolinski).

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4). When the larva completes its growth, it drops to the ground and pupates in the soil.

**Figure 4**. Larval stage of *Oulema melanopus* with characteristic feeding damage visible on leaf (Photo: M. Dolinski).

Week 5: Cereal Leaf Beetle

Cereal leaf beetle larvae eat the upper surface of leaves, leaving behind ‘windows’ of missing foliage that can look like white or yellow stripes on the leaves. Wheat is the preferred host of adult and larval cereal leaf beetle, but this pest will also consume barley, oats, rye, millet, wild oats, and other grasses.

In this picture, we see evidence of larval cereal leaf beetle feeding where green material is stripped from the leaf surface. We also see a female *Tetrastichus julis* parasitoid in the process of parasitizing a cereal leaf beetle larva! Picture by Emily Lemke and Karen Shamash, AAFC-Lethbridge.

Feeding damage caused by adult cereal leaf beetle does not typically result in yield loss to the crop. Rather, feeding damage caused by the larvae, especially to the flag leaf, results in lost yield and reduced crop quality.

In western Canada researchers expected cereal leaf beetle to become a widespread and problematic pest. This prediction has thankfully not yet come true, probably mostly due to the efficacy of an introduced parasitoid, Tetrastichus julis. Learn more about the parasitoid in one of the 2023 Insect of the Week posts!

Information about the biology of cereal leaf beetle and how to monitor for it was published by the Government of Alberta. You can also learn more by visiting the cereal leaf beetle page from the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide (available in French here).

Predicted Wheat Midge Development

Wheat midge (Sitodiplosis mosellana) emergence is reduced when soil moisture is insufficient to terminate spring diapause. Dry conditions in southcentral Manitoba as well as central and southern regions of Alberta have likely resulted in reduced emergence of larvae from the soil.

In regions where rainfall was sufficient to trigger the end of wheat midge diapause and the completeion of wheat midge development, we expect that eggs and larvae should be the most abundant life stages (Figs. 1 and 2).

**Figure 1. Proportion (%) of the wheat midge (*Sitodiplosis mosellana*) population that is predicted to be in the egg stage in western Canada, as of July 16, 2023.**

**Figure 2. Proportion (%) of the wheat midge (*Sitodiplosis mosellana*) population that is predicted to be in the larval stage in western Canada, as of July 16, 2023.**

Simulated development at Regina, Saskatchewan and Grande Prairie, Alberta indicates that adult emergence has peaked (Fig. 3). Development in the Peace River region is approximately 1 week behind development of wheat midge in eastern Saskatchewan.

Figure 3. Predicted development of wheat midge (*Sitodiplosis mosellana*) near Regina, Saskatchewan and in the Peace River region as of July 16, 2023. Note, Sm L1-2 in the legend refers to wheat midge larvae that are feeding in wheat heads. The model used to simulate wheat midge development was developed by Olfert et al. (figure by Ross Weiss, 2023).

It may still be important to be scouting for adult wheat midge in some areas of the prairies. For more information about scouting and economic thresholds for wheat midge, check out the wheat midge monitoring protocol and the Insect of the Week for Week 8, that featured wheat midge. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

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.

Predicted Wheat Midge Development

Wheat midge (Sitodiplosis mosellana) development is ahead of normal in 2023. Last week, wheat midge pupae were just beginning to appear at the soil surface. This week, where wheat midge populations are present, pupae should be the most abundant lifestage (Fig. 1).

**Figure 1. Proportion (%) of the wheat midge (*Sitodiplosis mosellana*) population that is expected to be in the pupal stage in western Canada, as of July 2, 2023.**

First emergence of adults was reported last week and the model indicates that peak emergence has not yet occurred. Model simulations indicate that eggs and larvae should be occurring in fields across Saskatchewan and western Manitoba (Fig. 2).

**Figure 2. Proportion (%) of the wheat midge (*Sitodiplosis mosellana*) population that is expected to be in the egg stage in western Canada, as of July 2, 2023.**

Based on the occurrence of wheat midge adults, field monitoring should begin now, if it has not started already. In order to assess wheat midge populations and to take the appropriate action for management, it is recommended that fields should be monitored when wheat is between heading and flowering. Field inspection should be carried out after 8:30 p.m. when the female midge are most active. Females are more active when the temperature is above 15°C and wind speed is less than 10 km/h. Wheat midge populations can be estimated by counting the number of adults present on four or five wheat heads.

For more information about scouting and economic thresholds, check out the wheat midge monitoring protocol and the Insect of the Week for Week 8, that featured wheat midge. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

Grasshoppers

Development of the pest grasshoppers continues to be ahead of schedule in 2023, as compared to past years. The first adult two-striped grasshoppers (Melonplus bivittatus) were collected on June 15 (Alberta) and June 19-20 (Saskatchewan). No one that we’ve spoken to remembers finding adult two-striped grasshoppers in June before. Especially in the southern prairies, densities are quite high and crop damage is being reported, as well as spraying to protect crops.

Model simulations were used to estimate development of grasshoppers as of July 2, 2023 and indicate that about 75% of the prairie grasshopper population should be in the 4^th or 5^th instar (Fig. 1). In an average year, we would expect 52% of the prairie grasshopper population to be in the 2^nd or 3^rd instar in early July (Fig. 2).

**Figure 1. Predicted grasshopper (*Melanoplus sanguinipes*) development, presented as average instar, across the Canadian prairies as of July 2, 2023.**

Figure 2. In an average year (based on 30-year average weather or climate normals), about 50% of the grasshopper population would be expected to be in the second or third 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.

Reports of adult occurrence suggest that adults are occurring much earlier than normal. The grasshopper model, developed for pest grasshoppers, indicates that adult grasshoppers should now be occurring across most of the southern prairies (Fig. 3).

Figure 3. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as the percent of the population that now in the adult stage, across the Canadian prairies as of July 2, 2023.

Geospatial maps are a tool to help time in-field scouting on a regional scale but grasshopper development can vary and is only accurately assessed through scouting. In Saskatchewan, grasshoppers have be observed in field crops. Monitor roadsides and field margins to assess the development and densities of local grasshopper populations.

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

Predicted wheat midge development

Wheat midge (Sitodiplosis mosellana) development is ahead of normal. Last week, wheat midge pupae were just beginning to appear at the soil surface. This week, where wheat midge populations are present, pupae should be the most abundant life-stage (Fig. 1). Recent rainfall in the Peace River region and Edmonton regions may have resulted movement of larvae to the soil surface and subsequent occurrence of pupae. First emergence of adults was reported last week.

**Figure 1. Percent of wheat midge (*Sitodiplosis mosellana*) that is predicted to be in the pupal stage in western Canada, as of June 25, 2023.**

Model simulations indicate that adults may be occurring in fields near Saskatoon, Regina, Estevan and Melita (Fig. 2). It is expected that adult populations may peak later next week. Oviposition is predicted to begin over the next few days.

**Figure 2. Percent of wheat midge (*Sitodiplosis mosellana*) that is predicted to be in the adult stage in western Canada, as of June 25, 2023.**

Based on the occurrence of wheat midge adults, field monitoring should begin now. In order to assess wheat midge populations and to take the appropriate action, it is recommended that fields should be monitored when wheat is between heading and flowering. Field inspection should be carried out after 8:30 p.m. when the female midge are most active. Females are more active when the temperature is above 15°C and wind speed is less than 10 km/h. Wheat midge populations can be estimated by counting the number of adults present on four or five wheat heads.

For more information about scouting, check out the wheat midge monitoring protocol and the Insect of the Week for Week 8, that featured wheat midge. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

Predicted Wheat Midge Development

Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Soil moisture conditions in May and June largely determine whether or not larvae exit cocoons to move to the soil surface to continue development (i.e., to pupate then emerge as adults this season). Adequate rainfall promotes termination of diapause and movement of larvae to the soil surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Wheat midge emergence may be delayed or erratic if rainfall does not exceed 20-30 mm during May and June.

Cumulative rainfall from May 1-June 18, 2023 across western Manitoba, most of Saskatchewan, and northwestern Alberta now exceeds the threshold (30 mm) required to terminate larval diapause. Though late, the rainfall event last week in the Edmonton region of Alberta may promote movement of larvae to the soil surface.

The wheat midge model indicates that, where wheat midge populations are present, larvae have begun to move to the soil surface (Fig. 1).

**Figure 1. Proportion (%) of the larval population of wheat midge (*Sitodiplosis mosellana*) that is expected to have moved to the soil surface across western Canada, as of June 18, 2023.**

Pupae are expected to be in the soil in the Peace River region, localized areas of Saskatchewan, and southwestern Manitoba (Fig. 2).

**Figure 2. Proportion (%) of the wheat midge (*Sitodiplosis mosellana*) population that is predicted to be in the pupal stage in western Canada, as of June 18, 2023.**

Model output suggests that first adults may be appearing in fields in southeastern Saskatchewan and southwestern Manitoba this week. Dr. Tyler Wist reports that adult wheat midge have been found on sticky cards baited with pheromone lures, including at the AAFC research farm in Saskatoon.

Scouting for adult wheat midge should start now. Over the next few weeks, the Prairie Pest Monitoring Network will continue to use phenology models to predict the status of wheat midge development and will provide additional updates.

For information about scouting, check out the wheat midge monitoring protocol. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.

CEREAL LEAF BEETLE

The cereal leaf beetle (Oulema melanopus) is an invasive insect pest that feeds on oat, barley, corn, rye, triticale, reed canary grass, ryegrass, fescue, wild oat, and millet, though wheat is their preferred host. Originally from Europe, it is now found in most cereal production areas in North America. The cereal leaf beetle can be found in parts of Manitoba, Saskatchewan, and Alberta.

Adult cereal leaf beetles are about 6 mm long and bear striking coloration with an orange-red thorax, yellow-orange legs, and a metallic blue head and wing covers. Adults overwinter in field debris in the fall, typically emerging in mid-April to May in the Canadian prairies to feed and lay their eggs. Cereal leaf beetle eggs are laid singly or in clusters of two or three along upper leaf surfaces, close to the margins or mid-rib. Initially appearing bright yellow, eggs darken to orange-brown and then black before hatching.

**Cereal leaf beetle larva. Photo credit: Dr. John Gavloski**

Larvae are the most damaging stage of this insect, feeding on upper leaf surfaces. Larval damage appears in pale lines similar in appearance to window-panes. Severe damage is similar to frost damage, where the leaves appear white and can also be mistaken for slug damage. Larvae are yellow in color with a brown head but may appear black like an oil droplet. Black coloration results from a defense mechanism, where larvae smear themselves with a fecal coating to mask their vibrant coloration and reduce predation. After feeding for 10 to 14 days, larvae drop to the soil, entering a pre-pupal and then pupal stage. Larvae pupate below the soil near the host plant’s roots for three weeks, after which they emerge as adults to feed and move to overwintering sites.

**Cereal leaf beetle damage to a cereal crop. Photo credit: Bob Hammon, Colorado State University, bugwood.org**

Monitoring for this pest should first occur in the spring, when producers should be on the lookout for adults emerging to feed. Scouting continues throughout the spring and summer, before and during the boot stage to assess cereal leaf beetle populations. Egg and larval scouting should be conducted at 5 to 10 random sites throughout the field, at least three meters from the edge. 10 consecutive plants should be inspected at each location, with the number of eggs and larvae counted per plant (before tillering) or per stem (after tillering). Following this, the average number of eggs and larvae is calculated per plant. Economic thresholds have not been established in Canada but have been established for Montana and North Dakota.

Tune in next week to learn about the cereal leaf beetle’s natural enemy – Tetrastichus julis!

Biological and monitoring information related to cereal leaf beetle in field crops is available online. For more information, visit the cereal leaf beetle page from 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).

Predicted grasshopper development

Model simulations were used to estimate development of grasshoppers as of June 4, 2023. Compared with average spring temperatures, well above normal temperatures across the prairies continue to result in rapid grasshopper development. Model runs suggest that this spring’s hatch is still proceeding with 68% of the hatch now complete (Fig. 1). In an average year, only 6% of the grasshopper hatch would be completed by this time in June. Hatch is predicted to be well underway across Alberta, western regions of Saskatchewan and southern Manitoba (Fig. 1).

**Figure 1. Predicted grasshopper (*Melanoplus sanguinipes*) hatch (%) across the Canadian prairies as of June 4, 2023.**

As of June 4, 32% of the grasshopper population is predicted to be in the egg stage, 34% first instar, 21% second instar, 12% third instar and 0.5% in the fourth instar. Based on average instar, development is most advanced across Alberta and a large area of Saskatchewan (Fig. 2). Field observations from June 7, 2023 agree with the model predictions.

**Figure 2. Predicted grasshopper (*Melanoplus sanguinipes*) development, presented as average instar, across the Canadian prairies as of June 4, 2023.**

In contrast to 2023, in an average year, most of the grasshopper population would still be in the egg stage or in the first instar stage at this time in early June.

Geospatial maps and model predictions are tools to help time in-field scouting on a regional scale but grasshopper development can vary and is only accurately assessed through scouting. Monitor roadsides and field margins to assess the development and densities of local grasshopper populations. Due to their small size, it may be difficult to visually observe first and second instar grasshoppers in roadside vegetation and field margins. If possible, use a sweep net to sample grasshoppers in ditches and along the edges of crops. Sweep net sampling allows for easier assessments of grasshopper densities at this time of year. Using the grasshoppers collected in sweep nets, we can also determine which life stages are present (which nymphal instars) and the species that are present. Information about grasshoppers and monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture, and Manitoba Agriculture.

Predicted wheat midge development

Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Adequate rainfall in May and June is a signal to larval cocoons to end their diapause and move to the soil surface to pupate. where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Wheat midge emergence may be delayed or erratic if rainfall does not exceed 20-30 mm during May. The Olfert et al. (2020) model indicated that dry conditions may result in:
a. Delayed adult emergence and oviposition
b. Reduced numbers of adults and eggs

Figure 1. Areas in western Canada where cumulative rainfall (mm) from May 1 to June 4, 2023 is sufficient (greater than 30 mm) to promote movement of wheat midge (*Sitodiplosis mosellana*) larvae to the soil surface.

In the last few weeks, rainfall events over parts of the prairies may have provided the cue to end wheat midge larval diapause. From May 1 to June 4, cumulative rainfall was normal or above normal in the Peace River region and parts of Saskatchewan (Fig. 1). Larvae, if present, are likely moving towards the soil surface in the Peace River region and in wet areas of Saskatchewan (Fig. 2).

**Figure 2. The proportion of the wheat midge (*Sitodiplosis mosellana*) larval population that has moved to the soil surface across western Canada, as of June 4, 2023.**

In contrast to the wet areas on the prairies, wheat midge adult emergence might be delayed in dry areas 2023. It is also possible that the wheat midge larval cocoons will remain in a diapause state until a future year when spring moisture is more suitable for wheat midge development.

Scouting for adult wheat midge usually starts in late June or early July. Over the next few weeks, the Prairie Pest Monitoring Network will continue to use phenology models to predict that status of wheat midge development and provide additional updates.

Predicted wheat stem sawfly growth

Warm, dry weather is conducive to wheat stem sawfly (Cephus cinctus) population growth where they are present. Risk of damage to sawfly host crops is greatest when weather conditions are warmer and drier than normal. Risk associated with wheat stem sawfly can be predicted by calculating growth index values, where the growth index describes the potential for wheat stem sawfly population growth. Where growth risk index values are moderate to high, crop damage is more likely than in areas where growth risk index values are low to moderate. Scouting in moderate and high risk areas this fall (especially where wheat stem sawfly populations are known to be present) will provide valuable information about potential crop yield losses this year and about the risk of wheat stem sawfly population damage in next growing season.

Based on growing season weather in 2022 (April 1 to August 22), predicted wheat stem sawfly growth index values are low to moderate across most of the prairies (Fig. 1). This is due to average (in parts of Alberta) to above-average (in parts Manitoba and southeastern Saskatchewan) precipitation during the current growing season. Growth index values, based on 2022 growing season weather are predicted to be greatest in a region that extends from Swift Current to Saskatoon (Fig. 1). This area has been warmer and drier than the rest of the prairies.

Figure 1. Predicted risk for wheat stem sawfly (*Cephus cinctus*) across the Canadian prairies as of August 21, 2022.

Access these resources for more information:
• Wheat stem sawfly was the Insect of the Week in 2021 for Week 12.
• Biological and monitoring information (including tips for scouting and economic thresholds) related to wheat stem sawfly is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, Alberta Agriculture and Forestry, and the Prairie Pest Monitoring Network.
• Refer to the wheat stem sawfly page 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.
• Review historical survey data for wheat stem sawfly.

Predicted wheat midge development

The following maps represent predicted regional estimates of wheat midge development. Remember – field level populations are assessed only through in-field scouting.

As of July 24, 2022, where wheat midge is present, model simulations predict that Albertan populations should be primarily in the egg stage, while populations across Manitoba and eastern Saskatchewan should consist of larvae developing in wheat heads (Fig. 1).

Regional differences in wheat midge development can be attributed to rainfall differences that occurred in May and June. Optimal rainfall in May and June across Saskatchewan and Manitoba has resulted in faster rates of wheat midge development rates than in Alberta. As a result, some adult wheat midge may still be active in Alberta (Fig. 2), while adult populations should have peaked and should be declining across Saskatchewan and Manitoba. Populations in the Peace River region are predicted to be primarily in the egg stage (Fig. 3). Across Manitoba and Saskatchewan, populations are predicted to be transitioning from the egg stage to the larval stage (Fig. 4). Wheat midge developmental rates near Regina, Saskatchewan are predicted to be greater than for Grande Prairie, Alberta.

Figure 2. Percent of wheat midge larval population (*Sitodiplosis mosellana*) that is in the adult stage, across western Canada, **as of July 24, 2022**.

Figure. 3. Percent of wheat midge population (*Sitodiplosis mosellana*) that is **in the egg stage** across western Canada, as of July 24, 2022.

Figure 4. Percent of wheat midge population (*Sitodiplosis mosellana*) that is in the larval stage (in wheat heads), across western Canada, as of July 24, 2022.

Model simulations indicate that egg development is complete and populations are primarily in the larval stage (>90%) for populations near Regina (Fig. 5) while Grande Prairie populations are predicted be in both egg (31%) and larval stages (61%) (Fig. 6). Potential risk continues to be greatest across eastern Saskatchewan and Manitoba.

Figure 5. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Regina, Saskatchewan** as of July 24, 2022.

Figure 6. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Grande Prairie, Alberta,** as of July 24, 2022.

In-Field Monitoring: The window for scouting and application of the economic threshold for wheat midge (i.e., during the synchrony between wheat anthesis and midge flight period) has now drawn to a close for 2022.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). Wheat midge was featured as the Insect of the Week in 2021 (for Wk07).

Predicted wheat midge development

The following maps represent predicted regional estimates of wheat midge development. Remember – the rate of development and density varies at the field level and can only be verified through in-field scouting. Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of adults on plants are carefully compared to the economic thresholds!

As of July 17, 2022, where wheat midge are present, model simulations predict that eggs and larvae (in heads) are the two prevalent stages occurring across the prairies. Differences in wheat midge development are attributed to rainfall differences across the prairies. Optimal rain events in May and June across Saskatchewan and Manitoba have contributed towards and advanced development rates of WM populations whereas populations in southern and central Alberta remain largely in the adult stage (Fig. 1). Adult populations in Saskatchewan and Manitoba are predicted to have peaked and are declining. Populations in the Peace River region are predicted to be primarily in the egg stage (Fig. 2). Across Manitoba and Saskatchewan, populations are predicted to be transitioning from the egg stage to the larval stage (Fig. 3).

Figure 1. Percent of wheat midge larval population (*Sitodiplosis mosellana*) that is in the pupal stage, across western Canada, **as of July 17, 2022**.

Figure. 2. Percent of wheat midge population (*Sitodiplosis mosellana*) that is **in the egg stage** across western Canada, as of July 17, 2022.

Figure 3. Percent of wheat midge population (*Sitodiplosis mosellana*) that is in the larval stage (in wheat heads), across western Canada, as of July 17, 2022.

Wheat midge development can be very site specific. For example, (as of July 17, 2022) developmental rates near Regina, Saskatchewan were predicted to be greater than for Yorkton, Saskatchewan, and Grande Prairie, Alberta. Model simulations indicate that populations near Regina were predominantly in the larval stage (Fig. 4) while Yorkton and Grande Prairie populations were predicted to be predominantly eggs (Figs. 5 and 6).

Figure 4. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Regina, Saskatchewan** as of July 17, 2022.

Figure 5. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Yorkton, Saskatchewan** as of July 17, 2022.

Figure 6. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Grande Prairie, Alberta,** as of July 17, 2022.

In-Field Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 5). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

Figure 5. Wheat midge (*Sitodiplosis mosellana*) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 6), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

**Figure** 6. *Macroglenes penetrans*, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. Photo: AAFC-Beav-S. Dufton.

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting! Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12). Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that actually regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

EUROPEAN CORN BORER: A GENERALIST PEST OF CROPS

Despite its common name, the European corn borer (Ostrinia nubilalis) feeds on many crop and non-crop plants including beans, potato, quinoa, millet, hemp, wheat, many vegetables and some flowers. European corn borer is occasionally an economic pest of crops such as corn and potatoes in Manitoba, where there is one generation per year. In parts of Ontario and eastern Canada, there are univoltine (one generation per year) and bivoltine (two generations per year) strains. How prevalent and damaging European corn borer is to many of its host crops is still not clear.

European Corn Borer larva in millet. Photo credit: John Gavloski, Manitoba Agriculture

European corn borer has traditionally been monitored in corn fields, and more recently in potato fields. However, a new harmonized protocol can be used to monitor for European corn borer in multiple crops. Anyone participating in insect monitoring on any potential host crop can access the harmonized protocol online or using the Survey123 app.

The protocol can be used to report the presence of European corn borer eggs, larvae, and crop damage. Anyone monitoring populations or encountering noticeable levels of European corn borer or their injury to any crop is highly encouraged to add this data. For more information about the harmonized protocol and to submit monitoring data, please click here to access all needed links. Information collected from across Canada will be used to better understand the distribution, feeding habits, and abundance of this pest.

European Corn Borer egg masses. Photo credit: John Gavloski, Manitoba Agriculture

Access these resources to find more information:
• Review the European corn borer page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) also accessible as a free downloadable PDF in either English or French on our new Field Guides page.
• Review the Manitoba Agriculture fact sheet for the European corn borer.
• Review the Ontario Ministry of Agriculture, Food, and Rural Affairs fact sheet for European corn borer.

Predicted wheat midge development

The following maps represent predicted regional estimates of wheat midge development. Remember – the rate of development and timing of adult midge emergence varies at the field level and can only be verified through in-field scouting. Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of adults on plants are carefully compared to the economic thresholds!

As of July 10, 2022 and where wheat midge is present, model simulations predict that pupae, adults, and eggs are present in wheat fields across the prairies. Differences in wheat midge development are attributed to rainfall differences across the prairies. Due to drier conditions in May and June, wheat midge development was delayed across most of Alberta. Alberta populations should be predominantly in the pupal stage (Fig. 1).

Figure 1. Percent of wheat midge larval population (*Sitodiplosis mosellana*) that is in the pupal stage, across western Canada, **as of July 10, 2022**.

The appearance of adults is predicted to increase across all three provinces (Fig. 2). Optimal rain in May and June across Saskatchewan and Manitoba has resulted in development rates that are greater than those predicted for Alberta. The simulation indicates that oviposition has begun across eastern Saskatchewan, Manitoba, the Peace River region and north-western Alberta (Fig. 3). Larvae may be in wheat heads in a region south of Winnipeg.

Figure. 2. Percent of wheat midge population (*Sitodiplosis mosellana*) that is **in the adult stage** across western Canada, as of July 10, 2022.

Figure 3. Percent of wheat midge population (*Sitodiplosis mosellana*) that is in the egg stage, across western Canada, as of July 10, 2022.

Adults may be occurring when wheat is most susceptible. Adults and eggs (top panel) are predicted to occur when wheat is heading (bottom panel) for fields near Regina, Saskatchewan (Fig. 3). Phenology simulations suggest that wheat may be susceptible for the next two weeks.

Figure 4. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Regina, Saskatchewan** as of July 10, 2022.

In-Field Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 5). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 6), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Thrips in small grains cereal crops

Thrips (used for both singular and plural) are members of the Order Thysanoptera. Even more confusing, there is also a genus of thrips named Thrips. That is, all Thrips are thrips but not all thrips are Thrips!

Thrips are characterized by small size (the largest species is only 2 mm as adults; the smallest is 0.6 mm), long slender bodies, and fringed wings (winged and wingless adults exist in some species). Males are smaller than females.

Figure 1: Adult thrips on barley leaf showing off fringed wings neatly folded over its abdomen. Photo: Sheila Elder, Saskatchewan, Canada

Adult thrips are generally relatively weak flyers and employ a‘clap and fling’ technique. The animal claps the leading edges of its wings together at the end of the upstroke then rotates the wings around the trailing edges, flinging them apart. Many small insects use this technique to promote air circulation and generate lift quickly. Pigeons also use this technique for their noisy flight initiations. For small insects, the viscosity of the air has a much greater effect than on larger animals. Fringed wings reduce drag associated with this effect.

There are about 6,000 species of thrips worldwide with 147 described species in two suborders in Canada, including 28 non-natives. Recent molecular work indicates that there may be as many as 255 additional as-yet-undescribed species in Canada. The most common and broadly distributed family is the Thripidae, followed by the Phlaeothripidae and Aeolothripidae. Other families are far less represented.

Although some species are important for pollination and a few are predators of other small insects, some are pests in crops. They have unique, asymmetrical mouthparts characterized by a greatly reduced right mandible. Their feeding is described as ‘rasping-sucking’: they scrape the surface of plant tissue and ingest fluid flowing from the wound. When feeding on actively growing plant tissue, growth reductions and distorted growth may be observed and yield loss can occur. When they feed on more mature tissue, silver leaf scars can occur that reduce the quality and marketability of some crops. Thrips are also important vectors of topsoviruses.

One suborder of thrips lays very small eggs (0.08 mm to 0.2 mm) singly in slits in plant tissue; the other lays eggs on plant surfaces. Eggs hatch into nymphs: juveniles resemble adults but are not sexually mature and have no wings. There are two juvenile feeding stages, followed by two non-feeding stages: pre-pupa and pupa.

The barley thrips, Limothrips denticornis, was first reported in North America in 1923 in New York. In its native Europe and Asia, it can be found on a wide variety of grass species but is a minor pest and only on rye. In North America, it is generally more important on barley, though it can be found on winter wheat, durum, winter rye, corn, and triticale. Adults are small (1.1 mm to 1.8 mm), elongate, and dark brown to black. These thrips lay eggs on upper leaf sheaths and each female can produce 100 eggs. Juveniles are smaller and lighter coloured. Barley thrips overwinter as adults and move to winter grasses in the spring. They are somewhat stronger flyers than many thrips species, but are still limited by their size. In Northern Europe, cereal thrips, including L. denticornis, have been reported to appearin large numbers ahead of thunderstorms. This may be associated with the warm conditions that precede these events, but it has also been suggested that they are sensitive to the electrical fields associated with storms.

Another cereal thrips, Limothrips cerealium, has also been reported in Canadian small grains cereals and was reported in 1928 to be responsible for 10 per cent losses in oats in Canada.

Thrips feeding on cereals can result in tissues appearing bleached. When numbers are high and feeding is intense, kernels can be shriveled. Severe flag leaf feeding can result in kernels filling improperly and reduced kernel weight.

Figure 2: Thrips nestled at the base of leaf. Photo: Sheila Elder, Saskatchewan, Canada

Scouting for barley thrips should be done from first sign of flag leaf until the head is completely emerged from the boot. Barley thrips can be found on stems but are more commonly under the top two leaf sheaths. Because thrips are relatively weak flyers, there may be greater concentrations in protected field edges. Greatest damage has been reported in dryland cropping areas after prolonged drought.

Economic thresholds:

Threshold (thrips/stem) = (Cost of control per acre / expected $ value per bushel) / 0.4

.Sample at least 50 stems from different parts of the field. One adult thrips per stem can cause a loss of 0.4 bushels per acre. This usually translates to an action threshold for barley and oats of 7 – 8 thrips/stem prior to head emergence but greater precision can be achieved by using the formula. The action threshold is the number of insects detected that can cause enough damage to justify the expense and effort of applying control. Numbers lower than this do not warrant control. Only apply control prior to the completion of heading.

Thresholds for cereal thrips have been determined for barley and oats but effects on other cereals crops in North America are less well understood. Work in Europe indicated comparable damage per thrips in rye, triticale, and winter barley. Recent reports of barley thrips in durum also suggest a risk of damaging effects, but these are not as well understood. A report from Germany indicated that, despite some relatively high thrips numbers, there was no correlation between barley thrips and damage. However, there is also evidence from Europe of the importance of long crop rotation to thrips damage control in wheat.

Predicted grasshopper development

The grasshopper (Acrididae: Melanoplus sanguinipes) model predicts development using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Model outputs provided below as geospatial maps are a tool to help time in-field scouting on a regional scale but local development can vary and is only accurately assessed through in-field scouting.

SCOUT NOW – Some areas of the Canadian prairies are presently experiencing high densities of nymphs and economically important species are present. Review lifecycle and damage information for this pest to support in-field scouting.

Warm, dry conditions across central and southern regions of Saskatchewan have resulted in rapid grasshopper development. Model simulations were used to estimate grasshopper development as of June 26, 2022. The grasshopper hatch is nearly complete for the southern prairies (Fig. 1). Hatch is still progressing across the Parkland and Peace River regions. Based on estimates of average nymphal development, first to fifth instar nymphs should be occurring across southern and central regions of all three prairie provinces (Fig. 2).

Figure 1. Predicted migratory grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of June 26, 2022.

Figure 2. Predicted migratory grasshopper (*Melanoplus sanguinipes*) development, presented as average instar, across the Canadian prairies **as of June 26, 2022**.

Grasshopper Scouting Tips:
● Review grasshopper diversity and photos of nymphs, adults, and non-grasshopper species to aid in-field scouting from egg hatch and onwards.
● Access the PPMN’s Grasshopper Monitoring Protocol as a guide to help implement in-field monitoring.
● Review grasshopper lifecycle, damage and scouting and economic thresholds to support sound management decisions enabling the preservation of beneficial arthropods and mitigation of economic losses.

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network. Also, refer to the grasshopper 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. Review the historical grasshopper maps based on late-summer in-field counts of adults performed across the prairies.

Predicted wheat midge development

The map in Figure 1 provides a visual representation of regional estimates of wheat midge movement to the soil surface, where pupal development will occur, then adults will begin to emerge. Remember – the rate of development and timing of adult midge emergence varies at the field level and can only be verified through in-field scouting. Fields within regions receiving sufficient rainfall should scout! Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of adults on plants are carefully compared to the economic thresholds.

As of June 26, 2022, model simulations predict that larvae (surface) and pupae are present with limited occurrence of adults. In terms of occurrence of pupae, wheat midge development is most advanced across central Saskatchewan, Manitoba and the Peace River region (British Columbia) (Fig. 1). The first appearance of adults is predicted near Regina and across southern Manitoba (Fig. 2). Model projections for July 3, 2022, indicate that the first appearance of adults should begin across the central prairies and Peace River region over the weekend.

Figure 1. Percent of wheat midge larval population (*Sitodiplosis mosellana*) that is in the pupal stage, across western Canada, **as of June 26, 2022**.

Figure. 2. Percent of wheat midge population (*Sitodiplosis mosellana*) that is in the adult stage, across western Canada, as of June 26, 2022.

In-Field Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Predicted wheat midge development

Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Where wheat midge cocoons are present in soil, the 2022 growing season’s rainfall during May and June should be sufficient to terminate diapause and induce the larvae to move to the soil surface. The map in Figure 1 provides a visual representation of regional estimates of wheat midge movement to the soil surface, where pupal development will occur, then adults will begin to emerge. Remember – the rate of development and timing of adult midge emergence varies at the field level and can only be verified through in-field scouting. Fields within regions receiving sufficient rainfall should soon scout! Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of wheat midge on plants are carefully compared to the economic thresholds.

As of June 19, 2022, wheat midge development is predicted to be most advanced in eastern Saskatchewan and the western Peace River region (British Columbia) (Fig. 1). The model was projected to July 10 (based on long-term average conditions) to predict potential wheat midge stages in early July. Simulations indicate that midge development will be more advanced at Estevan, Saskatchewan (Fig. 2) and Melfort, Saskatchewan (Fig. 3), than at Grande Prairie, Alberta (Fig. 4). Adults should begin to emerge in late June or early July.

Figure 1. Percent of wheat midge larval population (*Sitodiplosis mosellana*) that have moved to the soil surface across western Canada, **as of June 19, 2022**.

Figure 2. Predicted development of wheat midge (*Sitodiplosis mosellana*) populations near Estevan, Saskatchewan, as of June 19, 2022 **(projected to July 10, 2022, based on long-term average conditions)**

Figure 3. Predicted development of wheat midge (*Sitodiplosis mosellana*) populations near Melfort, Saskatchewan, as of June 19, 2022 **(projected to July 10, 2022, based on long-term average conditions)**

Figure 3. Predicted development of wheat midge (*Sitodiplosis mosellana*) populations near Grande Prairie, as of June 19, 2022 **(projected to July 10, 2022, based on long-term average conditions)**

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Predicted cereal leaf beetle development

The cereal leaf beetle (CLB) (Chysomelidae: Oulema melanopus) model predicts larval development using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Review lifecycle and damage information for this pest.

Warmer conditions in southern Alberta and western Saskatchewan are predicted to result in more rapid development of cereal leaf beetle (CLB) populations in those regions than in southern Manitoba. CLB model output predicts that hatch should be nearly complete for southern Alberta and western Saskatchewan. First to third instar larvae are predicted to be present in these areas (Fig. 1). As a result of cooler conditions, the model predicts that egg development has been delayed in southern Manitoba; first instar and second instar larvae may be appearing this week (Fig. 2).

Figure 1. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Lethbridge AB as of June 12, 2022.

Figure 2. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Winnipeg MB as of June 512 2022.

Predicted wheat midge development

Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil but soil moisture conditions in May and June largely determine whether or not the larva exits their cocoon to move to the soil surface to continue development (i.e., to pupate then emerge as a midge this season). Adequate rainfall promotes termination of diapause and movement of larvae to the soil surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Wheat midge emergence may be delayed or erratic if rainfall does not exceed 20-30 mm during May. The Olfert et al. (2020) model indicated that dry conditions may result in:
a. Delayed adult emergence and oviposition
b. Reduced numbers of adults and eggs

Compared to last week, the wheat midge model indicates that the development of larval populations has advanced considerably across the eastern prairies and Peace River region. Normal to above-normal rain in Manitoba, eastern Saskatchewan and the Peace River region should be sufficient to promote the movement of wheat midge larvae to the soil surface (Fig. 1). Insufficient rainfall across central Alberta and western Saskatchewan will limit the development of larval populations that are in the soil.

Wheat midge simulations suggest that greater than 60 % of the larval population has moved to the soil surface in some areas of the prairies. Larval populations should begin to transition to the pupal stage over the next seven days. Current development for eastern Saskatchewan and Manitoba is similar to long-term average rates.

Figure 1. Percent of wheat midge larval population (*Sitodiplosis mosellana*) that has moved to the soil surface across western Canada, **as of June 12, 2022**.

Risk estimates, based on meteorological inputs, were used to assess the impact of weather on wheat midge development and potential population growth potential (Fig. 2). Wheat midge risk is greatest in areas that have received normal to above-normal rainfall. As of June 12, 2022, model output indicates that potential risk is greatest across eastern Saskatchewan and Manitoba. Risk in these areas is predicted to be similar to long-term average risk.

Figure 2. Predicted risk for wheat midge (*Sitodiplosis mosellana*) outbreaks across the Canadian prairies as of June 12, 2022.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Predicted cereal leaf beetle development

Warmer conditions in southern Alberta and southwestern Saskatchewan are predicted to result in more rapid development of cereal leaf beetle (CLB) populations compared to southern Manitoba. CLB model output suggests that the hatch should be nearly complete for southern Alberta and Saskatchewan. First and second instar are predicted to be present in these areas (Fig. 1). As a result of cooler conditions, egg development is predicted to be delayed in southern Manitoba (Fig. 2). First instar larvae should begin to occur by the end of this week in Manitoba.

Figure 1. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Lethbridge AB as of June 5, 2022.

Figure 2. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Brandon MB as of June 5, 2022.

Predicted wheat midge development

Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Adequate rainfall promotes termination of diapause and movement of larvae to the soil surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al. (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. (2016) ran model simulations to demonstrate how rainfall impacts wheat midge population density. The Olfert et al. (2020) model indicated that dry conditions may result in:
a. Delayed adult emergence and oviposition
b. Reduced numbers of adults and eggs

As of June 5, 2022, normal to above normal rainfall in Manitoba, eastern Saskatchewan and the British Columbia Peace River region should be sufficient to promote the movement of wheat midge larvae to the soil surface this year (Fig. 1). Warmer temperatures in central Manitoba are expected to advance larval development over the next seven days. Current development for eastern Saskatchewan and Manitoba is similar to long-term average rates.

Figure 1. Percent of wheat midge larval population (*Sitodiplosis mosellana*) that has moved to the soil surface across western Canada, **as of June 5, 2022**.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Predicted cereal leaf beetle development

Warmer conditions in southern Alberta and southwest Saskatchewan are expected to have resulted in more rapid development of CLB populations in those areas than in southern Manitoba. The model output suggests that CLB hatch should be occurring across southern Alberta and Saskatchewan (Figs. 1 and 2). As a result of cooler conditions, egg development is predicted to be delayed in southern Manitoba (Fig. 3). The simulation predicts that second instar larvae may occur next week in southern Alberta and then 7-10 days later across southern Manitoba.

Figure 1. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Lethbridge AB as of May 29, 2022.

Figure 2. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Maple Creek SK as of May 29, 2022.

Figure 3. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Brandon MB as of May 29, 2022.

Predicted cereal leaf beetle development

Cereal leaf beetle (CLB) model output suggests that oviposition is underway across the southern prairies. The following graphs provide a comparison of development for Lethbridge, Alberta (Fig. 1) and Brandon, Manitoba (Fig. 2). Warmer conditions in southern Alberta are predicted to result in more rapid development of CLB populations than for southern Manitoba. The simulation predicts that first instar larvae may occur next week in southern Alberta and 7-10 days later across southern Manitoba.

Figure 1. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Lethbridge AB as of May 22, 2022.

Figure 2. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Brandon MB as of May 22, 2022.

Predicted cereal leaf beetle development

Cereal leaf beetle (CLB) model output suggests that overwintered adults are active and that oviposition is underway across southern regions across the southern prairies. Compared to simulations for climate normals, development is generally slower than average. The following graphs provide a comparison of development for Swift Current (Fig. 1) and Winnipeg (Fig. 2). Warmer conditions in southwestern Saskatchewan are expected to have contributed to more rapid development of CLB populations whereas cool conditions have contributed to slower development of CLB populations in southern Manitoba.

The simulation predicts that first instar larvae may occur during the third or fourth week of May.

Figure 1. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Swift Current SK as of May 15, 2022.

Figure 2. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Winnipeg MB as of May 15, 2022.

Predicted cereal leaf beetle development

As of May 8, 2022, the model output suggests that overwintered adults are active and that oviposition is underway across the southern regions of Alberta and in southwestern western Saskatchewan. Compared to simulations for climate normals, development in 2022 is generally slower than average. The graphs provide a comparison of development for Lethbridge (Fig. 1) and Swift Current (Fig. 2).

Warmer conditions in southern Alberta are predicted to result in more rapid development of CLB populations in comparison to southern Saskatchewan. The simulation indicates that first instar larvae may occur during the third week of May.

Figure 1. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Lethbridge AB as of May 8, 2022.

Figure 2. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Swift Current SK as of May 8, 2022.

Predicted wheat midge development

Wheat midge model simulations to August 8, 2021, predict that wheat midge populations should be in one of two larval stages. Where wheat midge is present, most larvae (55 %) will be in wheat heads, feeding on developing kernels. Development of this stage is predicted to be greatest across eastern Saskatchewan. Larvae that have completed development in wheat heads will be dropping to the soil where they will transition to larval cocoons (44 % of the prairie population). The occurrence of larval cocoons should be greatest across northwestern Saskatchewan and eastern Alberta. This stage will overwinter in the soil.

Figure 1. Percent of the wheat midge (*Sitodiplosis mosellana*) larval population that is predicted to be in wheat heads **as of August 8, 2021**.

Figure 2. Percent of the wheat midge (*Sitodiplosis mosellana*) larval population that is **predicted to be in the soil (larval cocoons) as of August 8, 2021**.

Monitoring: The window for scouting and application of the economic threshold for wheat midge (i.e., during the synchrony between wheat anthesis and midge flight period) has now drawn to a close for 2021.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

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

Predicted wheat midge development

The continued warm temperatures have resulted in the rapid development of wheat midge populations. Where present, wheat midge populations are predicted to be predominantly in the egg stage across most of the prairies (Fig. 1). This is a substantial change from last week where only 12 % of the population was predicted to be in the egg stage. The initial appearance of larvae (in wheat heads) is predicted to be occurring (Fig. 2).

Figure 1. Percent of wheat midge (*Sitodiplosis mosellana*) population that is **in the egg stage**, across the Canadian prairies **as of July 11, 2021**.

Figure 2. Percent of wheat midge (*Sitodiplosis mosellana*) population that is **in the larval stage (in wheat heads)**, across the Canadian prairies **as of July 11, 2021**.

The model was projected to July 27 to determine potential development at Regina (Fig. 3), Lacombe (Fig. 4), and Grande Prairie (Fig. 5) over the next two weeks. The model output suggests that oviposition will continue to increase over the next 5-7 days and should peak sometime this week. Larvae (Sm L1-2) are expected to complete development by the end of July. Macroglenes penetrans, a parasitoid of wheat midge, is active in wheat fields when wheat midge adults are present. Simulation runs indicate that the parasitoid has begun to appear in wheat crops in fields near Regina.

Figure 3. Predicted development of wheat midge (*Sitodiplosis mosellana*) near Regina, Saskatchewan **as of July 11, 2021 (projected to July 27, 2021)**.

Figure 4. Predicted development of wheat midge (*Sitodiplosis mosellana*) near Lacombe, Alberta **as of July 11, 2021 (projected to July 27, 2021)**.

Figure 5. Predicted development of wheat midge (*Sitodiplosis mosellana*) near Grande Prairie, Alberta as of July 11, 2021 (projected to July 27, 2021).

If not already underway, scout for wheat midge adults this week and especially in regions where higher densities are predicted to occur. It is especially important to be monitoring for adults at dusk in regions expected to be at high risk, based on the 2020 survey which is mapped here.

Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 7). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

**Figure** 7. Wheat midge (*Sitodiplosis mosellana*) laying their eggs on the wheat heads
(Photo: AAFC-Beav-S. Dufton & A. Jorgensen).

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 8), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

**Figure** 8. *Macroglenes penetrans*, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. (Photo: AAFC-Beav-S. Dufton).

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Predicted wheat midge development

The recent warm temperatures have resulted in rapid development of wheat midge (Sitodiplosis mosellana) populations. Dry conditions in the Peace River region have contributed to delayed development of larval cocoons with 30-75 % of the population not expected to emerge this growing season. Unlike the larval cocoon stage (located in the soil), development of pupal, adult, egg and larval stages (in wheat heads) is not dependent on moisture. Development of these stages are dependent on temperature.

Where present, wheat midge populations should be entering the adult stage across most of the prairies (Fig. 1). This is a substantial change from last week where less than 10 % of the population was predicted to be in the adult stage. Oviposition is predicted to be occurring across most of the prairies and the initial hatch is now expected for southern Manitoba and southeastern Saskatchewan (Figs. 2 and 3).

Figure 1. Percent of wheat midge (*Sitodiplosis mosellana*) population that is in the adult stage, across the Canadian prairies **as of July 4, 2021**.

Figure 2. Percent of wheat midge (*Sitodiplosis mosellana*) population that is **in the egg stage**, across the Canadian prairies **as of July 4, 2021**.

Figure 3. Percent of wheat midge *(Sitodiplosis mosellana*) population that is **in the larval stage (in wheat heads)**, across the Canadian prairies **as of July 4, 2021**.

The model was projected to July 20 to determine potential development at Regina (Fig. 4), Lacombe (Fig. 5), and Grande Prairie (Fig. 6) over the next two weeks. Output suggests that oviposition will rapidly increase over the next 10 days and wheat crops near all three locations may be susceptible for the next two weeks. Based on the predicted occurrence of adults and eggs, development is most rapid where populations were predicted to be greatest in 2021 (based on 2020 fall survey).

Figure 4. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Regina, Saskatchewan** **as of July 4, 2021 (projected to July 20, 2021)**.

Figure 5. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Lacombe, Alberta** **as of July 4, 2021 (projected to July 20, 2021)**.

Figure 6. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development **near Grande Prairie, Alberta** **as of July 4, 2021 (projected to July 20, 2021)**.

Macroglenes penetrans is a parasitoid of wheat midge that is active in wheat fields when wheat midge adults are present. Model simulations indicate that the parasitoid has begun to appear in wheat crops in fields near Regina (Fig. 7).

Figure 7. Predicted occurrence of wheat midge (*Sitodiplosis mosellana*) and *Macroglenes penetrans* adults near Regina, Saskatchewan as of July 4, 2021 (projected to July 20, 2021).

If not already underway, scouting for wheat midge adults should continue this week and especially in regions where higher densities are predicted to occur. It is especially important to be monitoring for adults at dusk in regions expected to be at high risk, based on the 2020 survey which is mapped here.

Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 7). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 8), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Predicted wheat midge development

This week, wheat midge model simulations indicate that the majority of the larval population has moved to the soil surface (Figure 1). Dry conditions in the Peace River region have resulted in delayed development of larval cocoon populations. Pupae should now be occurring across most of the prairies (Figure 2). First appearance of adults is predicted across Manitoba and most of Saskatchewan (Figure 3).

Figure 1. Percent of the wheat midge (*Sitodiplosis mosellana*) larval population that has moved to the soil surface across the Canadian prairies **as of June 27, 2021**.

Figure 2. Percent of wheat midge (*Sitodiplosis mosellana*) population that is in the pupal stage, across the Canadian prairies **as of June 27, 2021**.

Figure 3. Percent of wheat midge (*Sitodiplosis mosellana*) population that is in the adult stage, across the Canadian prairies **as of June 27, 2021**.

The model was projected to July 13 to determine potential development at Regina (Fig. 4), Lacombe (Fig. 5), and Grande Prairie (Fig. 6) over the next two weeks.

Figure 4. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development near Regina, Saskatchewan **as of June 27, 2021 (projected to July 13, 2021)**.

Figure 5. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development near Lacombe, Alberta as of June 27, 2021 (projected to July 13, 2021).

Figure 6. Predicted development of wheat midge (*Sitodiplosis mosellana*) and wheat development near Grande Prairie, Alberta as of June 27, 2021 (projected to July 13, 2021).

Compared to Lacombe and Grande Prairie, Regina has been warmer and wetter for the period of May 1 – June 27, 2021, resulting in advanced development of larvae and pupae (Fig. 4). In the Regina and Lacombe areas, initial oviposition is predicted to occur this week (Figs. 4 and 5). Emergence patterns for southern Manitoba are predicted to be similar to Regina. Cooler and dryer conditions in the Peace River region are expected to have impacted the movement of larvae to the soil surface, resulting in reduced adult emergence and later appearance of adults. Oviposition in the southern Peace River region is predicted to occur during the first week of July (Figure 6). Wheat crops near all three locations may be susceptible for the next 14-17 days.

If not already underway, scouting for wheat midge adults should begin this week and especially in regions where higher densities are predicted to occur. It is especially important to be monitoring for adults at dusk in regions expected to be at high risk, based on the 2020 survey which is mapped here.

Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 7). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 8), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Alert: Predicted wheat midge development

Wheat midge model simulations indicate that the majority of the larval population has moved to the soil surface (Fig. 1). Dry conditions in the Peace River region have resulted in delayed development of larval cocoon populations. First appearance of pupae should be occurring near Winnipeg, Brandon, Regina and Edmonton areas (Fig. 2).

Figure 1. Percent of the wheat midge (*Sitodiplosis mosellana*) larval population that has moved to the soil surface and is preparing to pupate across western Canada, based on weather conditions **up to June 20, 2021**.

Figure 2. Percent of wheat midge (*Sitodiplosis mosellana*) population that is in the pupal stage, located near the soil surface across western Canada, based on weather conditions **up to June 20, 2021**.

The model was projected to July 6 to determine potential development at Regina, Lacombe and Grande Prairie over the next two weeks. Compared to Lacombe and Grande Prairie, Regina has been warmer and wetter for the period of May 1 – June 20, 2021 (Fig.3). The first appearance of adults in the Regina area is expected to occur this week and initial oviposition is predicted to occur by the end of June. Emergence patterns for southern Manitoba are predicted to be similar to Regina.

Figure 3. Predicted development of wheat midge (*Sitodiplosis mosellana*) populations near Regina, Saskatchewan as of June 20, 2021 (projected to July 6, 2021).

Cooler temperatures at Lacombe are predicted to result in slower development of larvae and pupae (relative to Regina) with the first emergence of adults predicted to occur during the last week of June (Fig. 4). Cooler and dryer conditions in the Peace River region will impact the movement of larvae to the soil surface, resulting in reduced adult emergence and later appearance of adults; adult emergence is predicted to occur during the first week of July (Fig. 5).

Figure 4. Predicted development of wheat midge (*Sitodiplosis mosellana)* populations near Lacombe, Alberta as of June 20, 2021 (projected to July 6, 2021).

Figure 5. Predicted development of wheat midge (*Sitodiplosis mosellana*) populations near Grande Prairie, Alberta as of June 20, 2021 (projected to July 6, 2021).

Based on predictions for adult emergence, monitoring for the appearance of wheat midge adults should begin this week in Manitoba and Saskatchewan and later next week across Alberta in areas where wheat midge is expected to occur. It is especially important that adult monitoring be prioritized in regions with high risk based on the 2020 survey (Fig. 6).

Figure 6. 2021 Wheat midge forecast map which represents regions at risk of damage to cereal crops due to wheat midge, based on the number of un-parasitized wheat midge larval cocoons in soil samples collected in the fall of 2020.

Monitoring: When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 7). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 8), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.

Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting! Additionally, the differences between midges and parasitoid wasps was featured as the Insect of the Week in 2019 (for Wk12). Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that actually regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Cereal Aphid Manager APP

Aphids can cause significant damage to fields and increase crop losses but low densities in a grain field sometimes have little economic impact on production. This is especially true if the aphid’s natural enemies (beneficial insects) are present in the field because they can keep the aphids under control.

The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist’s (AAFC-Saskatoon) Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:

the number of aphids observed and how quickly they reproduce
the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.

Frequent in-field scouting, supported by the app’s dynamic threshold, allows growers to weigh the above factors and the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.

To learn more and to download the app (Android or iOS), go to AAFC’s CAM webpage.

Predicted wheat midge development

As of June 6, 2021, wheat midge model runs indicate that recent rainfall in central Alberta and northwestern and southeastern Saskatchewan has resulted in movement of more than 30 % of the larval population to the soil surface (Fig. 1). Dryer conditions in other parts of Saskatchewan, Manitoba and most of the Peace River region continue to delay movement of larvae to the soil surface. If dry conditions persist, this should result in delayed pupation and adult emergence.

Figure 1. Percent of wheat midge larval population (*Sitodiplosis mosellana*) that has moved to the soil surface across western Canada, **based on weather conditions up to June 6, 2021**.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Predicted cereal leaf beetle development

The cereal leaf beetle (CLB) (Oulema melanopus) model predicts that larval development is progressing across the prairies. The graphs below provide a comparison of development at Saskatoon (Fig. 1) and at Lethbridge (Fig. 2). The simulation indicates that populations are mostly in the second instar with the initial occurrence of third instar stages expected to occur this week. The simulation predicts that larval development will be complete by the end of the month across central Saskatchewan.

Figure 1. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Saskatoon, Saskatchewan **as of June 6, 2021 (projected to June 22, 2021**).

Figure 2. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Lethbridge, Alberta **as of June 6, 2021 (projected to June 22, 2021**).

Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (2018; accessible in either English-enhanced or French-enhanced versions).

Predicted cereal leaf beetle development

The cereal leaf beetle (CLB) model predicts that egg hatch is progressing across the prairies. The graphs provide a comparison of development at Lacombe (Fig. 1) and at Lethbridge (Fig. 2). The simulation indicates that second instar larvae will be observed over the next few days.

Figure 1. Predicted status of cereal leaf beetle (Oulema melanopus) populations near Lacombe, Alberta as of May 30, 2021 (projected to June 15, 2021).

Figure 2. Predicted status of cereal leaf beetle (Oulema melanopus) populations near Lethbridge, Alberta **as of May 30, 2021 (projected to June 15, 2021).**

Lifecycle and Damage:

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4). When the larva completes its growth, it drops to the ground and pupates in the soil.

Cereal leaf beetle development

The cereal leaf beetle (CLB) model output predicts that egg hatch may be starting across the prairies. The graphs provide a comparison of development at Saskatoon (Fig. 1) and at Lethbridge (Fig. 2). The simulation indicates that second instar larvae may occur during the last week of May near Saskatoon and Lethbridge.

Figure 1. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Saskatoon, SK
**as of May 23, 2021 (projected to June 7, 2021)**.

Figure 2. Predicted status of cereal leaf beetle (*Oulema melanopus*) populations near Lethbridge, AB
as of May 23, 2021 (projected to June 7, 2021).

Lifecycle and Damage:

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4). When the larva completes its growth, it drops to the ground and pupates in the soil.

Pestiferous slugs and their parasites

Researchers based at the University of Alberta are conducting a survey of pestiferous slugs and their associated nematode parasites from agricultural fields of Alberta. Last year, a peer-reviewed article was published (Nematology2020) which reported for the first time the presence of a parasitic nematode in Canada. The parasite can kill slugs and could have a role as a potential biocontrol agent against slug populations.

The slug survey continues this summer with researchers hoping to connect with producers who are interested in participating. If interested, please contact researchers at slugs@ualberta.ca now to participate by:
● Either allowing U of A staff to collect slugs from fields (1-2 times/month) or
● Arranging to send live slugs encountered in the field (please email first to obtain detailed collection instructions).

Email slugs@ualberta.ca to obtain more information.

Figure 1. Flag leaf feeding damage on wheat caused by the grey field slug (Deroceras reticulatum).
Photo taken near Crooked Creek AB on August 2, 2018, by J. Otani.

Cereal leaf beetle development

The cereal leaf beetle (CLB) model output predicts that oviposition is underway across the prairies. The graphs provide a comparison of development at Saskatoon (Fig. 1) and at Lacombe (Fig. 2). The simulation indicates that first instar larvae may occur during the third week of May near Saskatoon and one week later at Lacombe.

Figure 1. Predicted status of cereal leaf beetle populations near Saskatoon, SK as of May 16, 2021 (projected to May 31, 2021).

Figure 2. Predicted status of cereal leaf beetle populations near Lacombe, AB as of May 16, 2021 (projected to May 31, 2021).

Lifecycle and Damage:

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4). When the larva completes its growth, it drops to the ground and pupates in the soil.

Field heroes

The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Check the recently updated Field Heroes website for scouting guides, downloadable posters, and videos. Learn about these important organisms at work in your fields!

Two NEW Field Heroes resources for 2021 include:

The NEW Pests and Predators Field Guide is filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download for free to arm your in-field scouting efforts!
Real Agriculture went live in 2021 with Season 2 of the Pest and Predators podcast series!
• NEW – Episode 10 – Good bugs relocate for work (June 1, 2021)
• Episode 9 – Secret agents in the stubble (May 18, 2021)
• Episode 8 – Good vs pea leaf weEVIL (May 4, 2021)
• Episode 7 – Powerful parasitoids: Better than fiction (April 20, 2021)
• Recap of SEASON 1: Episode 1 – Do you know your field heroes? Episode 2 – An inside look at the Prairie Pest Monitoring Network. Episode 3 – How much can one wasp save you? Episode 4 – Eat and be eaten — grasshoppers as pests and food Episode 5 – Killer wasp has only one target — wheat stem sawfly Episode 6 – Plentiful parasitoids

Access ALL the Field Heroes links here and be sure to follow @FieldHeroes!

Wireworms

Newly seeded fields should be scouted throughout the germination and emergence periods for a variety of insect pests – one of the most difficult to detect can be wireworms! Wireworms are the juvenile stages of a complex comprised of several species of Elateridae, commonly referred to as ‘Click beetles’. On the Canadian prairies, wireworm collections from field crops indicate that three economically important species of wireworms or click beetles can be present; Selatosomus destructor, Limonius californicus, and Hypnoides bicolor. According to van Herk and Vernon (2014), a wide variety of Elateridae have been described from across the Canadian prairies; Alberta 144 species described in Alberta, 108 species described from Saskatchewan, and 109 species described from Manitoba.

Review these two wireworm posts to learn more and supplement in-field scouting:

Wireworms – Insect of the Week (2018)

Wireworm distribution map – Weekly Update (2018)

Biological and monitoring information related to wireworms in field crops is posted by Manitoba Agriculture and Resource Development, and Alberta Agriculture and Forestry. Also, refer to the wireworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018; accessible in either English-enhanced or French-enhanced versions).

Cereal leaf beetle development

The cereal leaf beetle (CLB) model output suggests that overwintered adults are active and that oviposition is underway across the prairies. The graphs provide a comparison of development for Saskatoon (Fig. 1) and Winnipeg (Fig. 2). The simulation indicates that first instar larvae may occur during the third week of May.

**Figure 1**. Predicted status of cereal leaf beetle populations near Saskatoon, SK as of May 9, 2021.

**Figure 2**. Predicted status of cereal leaf beetle populations near Winnipeg MB as of May 9, 2021.

Lifecycle and Damage:

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4). When the larva completes its growth, it drops to the ground and pupates in the soil.

Cereal leaf beetle development

Figure 1. Predicted status of cereal leaf beetle populations near Lethbridge AB *as of May 2, 2021*.

Figure 2. Predicted status of cereal leaf beetle populations near Saskatoon SK *as of May 2, 2021*.

Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 3). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They emerge in the spring once temperatures reach 10-15 ºC and the adults are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.

Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4). When the larva completes its growth, it drops to the ground and pupates in the soil.

Predicted wheat midge development

Cool, wetter growing seasons generally favour wheat midge development. Wheat midge larvae overwinter in the soil in larval cocoons. Adequate soil moisture (May-June) is required to terminate diapause, resulting in movement of larvae to the soil surface. The wheat midge model was run to determine potential numbers of overwintering wheat midge larvae.

During May and June weather conditions were cooler and wetter than normal across most of Alberta. These model runs indicated that weather conditions that would promote diapause termination and movement of larvae to the soil surface were favourable, and may have resulted in higher than average adult populations in early July. Conversely, warm, dry conditions occurred across most of Manitoba and were not suitable for larval development during May and June. Figure 1 represents the potential number of larval cocoons (as of August 17, 2020). Densities of wheat midge larval cocoons were predicted to be greater across Alberta than Saskatchewan and Manitoba (Fig. 1). Figure 2 provides a comparison of densities for the same time period in 2019. Low densities in 2019 were attributed to well below normal precipitation during the period of April to June (Fig. 2).

**Figure 1**. Predicted number of larval cocoons of wheat midge (*Sitodiplosis mosellana*) across the Canadian prairies as of August 17, 2020.

**Figure 2**. Predicted number of larval cocoons of wheat midge (*Sitodiplosis mosellana*) across the Canadian prairies as of August 17, 2019.

Review information supporting in-field monitoring for wheat midge (Fig. 3) and its parasitoid, Macroglenes penetrans (Fig. 4), posted back on Week 14 of the 2020 growing season.

This image has an empty alt attribute; its file name is 2016Jul12_IMG_2298_DuftonJorgensen_AAFC%2B%2528revised%2529.jpg — **Figure 3**. Wheat midge (*Sitodiplosis mosellana*) laying their eggs on the wheat heads
(Photo: AAFC-Beaverlodge-S. Dufton & A. Jorgensen).

This image has an empty alt attribute; its file name is 2016Jul12_IMG_2154_DuftonJorgensen_AAFC%2B%2528revised%2529.jpg — **Figure 4**. *Macroglenes penetrans*, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. (Photo: AAFC-Beaverlodge-S. Dufton).

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages 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.

Ladybird beetles and mummies

Ladybird beetle larvae (Fig. 1), pupae (Fig. 2), and adults (Fig. 3) can all be found in fields at this time of year. Take a look at the various stages and the many patterns of native and introduced species to recognize these as Field Heroes! Ladybird beetles are categorized as general predators and will feed on several species of arthropods but are partial to aphids.

**Figure 1**. Ladybird beetle larva (photo credit: AAFC-Beaverlodge)

**Figure 2**. Ladybird beetle pupa (photo credit: AAFC-Beaverlodge).

**Figure 3**. Ladybird beetle (*Coccinella septempunctata*) (photo credit: AAFC-Beaverlodge)

Another “beneficial” found in fields at this point in the season are mummified aphids (Fig. 4). The “mummy” contains a maturing parasitoid wasp which will emerge from the host and seek other aphids to parasitize. Read more about the amazing Aphidiinae wasps by accessing the pages from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide“. The guide is available as a free downloadable document in both an English-enhanced or French-enhanced version.

**Figure 4**. An aphid “mummy” adhered to a wheat awn. A “mummy” is the aphid host transformed to enclose a soon-to-emerge parasitoid wasp (photo credit: AAFC-Beaverlodge).

Wheat midge

Click to link to last week’s information posted for Wk 13 (released 23Jul2020) to review the predictive model outputs for this insect pest.

Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 1). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

**Figure 1**. Wheat midge (*Sitodiplosis mosellana*) laying their eggs on the wheat heads
(Photo: AAFC-Beav-S. Dufton & A. Jorgensen).

REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 2), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.

**Figure 2**. *Macroglenes penetrans*, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. (Photo: AAFC-Beav-S. Dufton).

Economic Thresholds for Wheat Midge:

a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.

b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.

Inspect the developing kernels for the presence of larvae and the larval damage.

Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week in 2019 (for Wk11). Review that post for descriptions and photos to help with in-field scouting for this economic pest of wheat! Additionally, the differences between midges and parasitoid wasps were featured as the current Insect of the Week in 2019 (for Wk12). Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Predicted wheat midge development

This week (as of July 19, 2020), regions of the Canadian prairies are either at a sensitive time for wheat midge monitoring OR the opportunity to scout and apply insecticides to prevent adult midge from laying eggs may have passed. Scouting remains essential now, especially in areas where wheat midge development was slightly delayed according to last week’s model output (Table 1). Note that the model predicted populations near Lethbridge, Grande Prairie and Lacombe would be at 90% emergence on July 23, July 25, and July 26, respectively.

This week, wheat midge model runs indicate that, where wheat midge are present and rainfall has been adequate, adult emergence is well underway and oviposition is occurring, and early instar larvae may be present and beginning to feed on developing wheat kernels. Low rainfall amounts across large areas of Manitoba and Saskatchewan has resulted in delayed adult emergence, resulting in lower egg densities, according to our model.

**Figure 1**. Predicted wheat midge (*Sitodiplosis mosellana*) phenology at Saskatoon SK.
Values are based on model simulations (April 1-July 19, 2020).

**Figure 2**. Predicted wheat midge (*Sitodiplosis mosellana*) phenology at Lacombe AB.
Values are based on model simulations (April 1-July 19, 2020).

Figure 3 compares synchrony between wheat midge and wheat development for fields near Saskatoon. The graph indicates that peak adult emergence and oviposition are likely to occur during anthesis; wheat susceptibility decreases once the crop is flowering (Fig. 3). Figure 4 compares the predicted phenology near Saskatoon of wheat midge adults with Macroglenes penetrans, a parasitoid of wheat midge. The parasitoid wasp seeks out and lays eggs in wheat midge eggs. The graph shows that emergence/oviposition of wheat midge adults and M. penetrans are similar (Fig. 4). Taken together, this information can be used as a guide to determine when fields should be monitored.

**Figure 3**. Comparison of predicted phenology of wheat midge (*Sitodiplosis mosellana*) and wheat at Saskatoon SK as of July 19, 2020.

**Figure 4**. Comparison of predicted phenology of wheat midge (*Sitodiplosis mosellana*) and its parasitoid, *Macroglenes penetrans*, at Saskatoon SK *as of July 19, 2020*.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Predicted wheat midge development

Wheat midge model runs indicate that, where wheat midge are present, adult emergence is well underway and oviposition is occurring across most prairie locations. The map suggests that, as of July 12, 2020, populations are primarily in the egg stage (Fig. 1). Low rainfall amounts across large areas of Manitoba and Saskatchewan has resulted in delayed adult emergence, resulting in lower egg densities.

**Figure 1**. Predicted percent of population of wheat midge (*Sitodiplosis mosellana*) at adult stage across the Canadian prairies (as of July 12, 2020).

The next 10-14 days are very important for monitoring wheat midge populations for the purpose of making management decisions. Simulations were run to July 26 to assess population development over the next 10 days (Table 1). The following table indicates that 50% emergence of adults should occur this week at Saskatoon and next week at Lacombe (Table 1). This week populations in Manitoba are predicted to be at 90% adult emergence (Table 1).

The two graphs below illustrate the development of wheat midge populations near Saskatoon (Fig. 2) and Lacombe (Fig. 3). Adult numbers are currently peaking near Saskatoon while adult emergence near Lacombe is not expected to peak until next week.

**Figure 2**. Predicted wheat midge (*Sitodiplosis mosellana*) phenology at Saskatoon SK *projected to July 21, 2020*.

**Figure 3**. Predicted wheat midge (*Sitodiplosis mosellana*) phenology at Lacombe AB *projected to July 21, 2020*.

The next two graphs compare the synchrony between wheat midge and wheat for fields near Lacombe (Fig. 4). The graph indicates that peak adult emergence and oviposition may occur during anthesis; wheat susceptibility decreases once the crop is flowering (Fig. 4).

**Figure 4**. Comparison of predicted phenology of wheat midge (*Sitodiplosis mosellana*) and wheat at Lacombe AB projected to July 21, 2020.

The last graph compares phenology (Saskatoon) of wheat midge adults with Macroglenes penetrans, a parasitoid of wheat midge (Fig. 5). The parasitoid wasp lays eggs in wheat midge eggs. The graph shows that emergence/oviposition of wheat midge adults and M. penetrans are similar (Fig. 5). This information can be used as a guide to determine when fields should be monitored.

**Figure 5**. Comparison of predicted phenology of wheat midge (*Sitodiplosis mosellana*) and its parasitoid, *Macroglenes penetrans*, at Saskatoon SK *projected to July 21, 2020*.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Predicted wheat midge development

Wheat midge overwinter as larval cocoons in the soil. Soil moisture conditions in May and June can have significant impact on wheat midge emergence. Adequate rainfall promotes termination of diapause and movement of larval to the sol surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al. (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. (2016) ran model simulations to demonstrate how rainfall impacts wheat midge population density. Our wheat midge model (Olfert et al. 2020) indicates that dry conditions may result in: (a) Delayed adult emergence and oviposition, (b) Reduced numbers of adults and eggs.

Wheat midge model runs indicate that, where wheat midge are present, pupation is occurring across Alberta, northwest Saskatchewan and southern Manitoba (Fig. 1). Simulations suggest that, though still less than 15%, adult emergence has begun, most notably across Alberta (Fig. 1). Females lay eggs on developing wheat heads. This typically occurs in evenings when winds are calm. Wheat midge monitoring protocol suggests that wheat fields should be inspected for adults in late June and early July as wheat heads are emerging. The next three weeks are very important for monitoring wheat midge populations for the purpose of making management decisions.

**Figure 1**. Predicted percent of population of wheat midge (*Sitodiplosis mosellana*) at adult stage across the Canadian prairies (as of July 5, 2020).

Simulations were run to July 21 to assess population development over the next two weeks (Figs. 2-4). The first graph illustrates development of wheat midge populations near Saskatoon (Fig. 2). Adult emergence has begun and should peak next week, suggesting that monitoring fields for adults should begin in the next few days. Oviposition has just started and larvae will occur soon after.

The second graph compares synchrony between wheat midge and wheat for fields near Lacombe (Fig. 3). The graph indicates that adult emergence and oviposition may occur this year when the crop is most susceptible.

**Figure 3**. Comparison of predicted phenology of wheat midge (*Sitodiplosis mosellana*) and wheat at Lacombe AB projected to July 21, 2020.

The last graph compares phenology of wheat midge adults near Saskatoon with the phenology of Macroglenes penetrans, a parasitoid of wheat midge (Fig. 4). The parasitioid wasp lays is eggs inside wheat midge eggs. The graph shows that the timing of emergence and oviposition of wheat midge adults is similar to the emergence and oviposition timing of M. penetrans. All of this information can be used as a guide to determine when fields should be monitored.

**Figure 4**. Comparison of predicted phenology of wheat midge (*Sitodiplosis mosellana*) and its parasitoid, *Macroglenes penetrans*, at Saskatoon SK *projected to July 21, 2020*.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Cereal Aphid Manager

the number of aphids observed and how quickly they reproduce
the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.

To learn more and to download, go to AAFC’s CAM webpage.

Wanted – Slugs in field crops

Reminder
This year, wet field conditions contributed to slug issues in cereals and canola. Researchers based at the University of Alberta are seeking live slug samples from field crops. Please take note of their collection protocol and help, if possible please!

Watch for feeding channels on the upper surfaces of the flag leaf in wheat and plan to scout in the evening!

Figure 1. Deroceras reticulatum, the “grey field slug”, on wheat growing near Crooked Creek AB (August 2, 2018; det. Lien Luong).

Grey garden slugs were observed when field scouting was performed in the evening from 8:30-10:30pm in 2018 (Fig. 1 and 2). As the temperatures decreased, the slugs moved up the wheat stems, climbing to the topside of the flag leaf and onto the wheat heads although they did not appear to feed at the developing kernels. Wheat was hand-collected by clipping stems ~20cm above the ground and these samples later revealed a density of 1.04 slugs per stem (n=465 stems) causing the above damage (Fig. 2).

Figure 2. Flag leaf feeding damage on wheat caused by the grey field slug (Deroceras reticulatum). Photo taken near Crooked Creek AB on August 2, 2018, by J. Otani.

Specimens were forwarded to L. Luong (U of A) who identified the slugs from the above field as one species, Deroceras reticulatum, the grey field slug. The majority were juveniles. The grey field slug is the most common to occur in the home garden.

Thanks to Dr. John Gavloski (Manitoba Agriculture) who prepared the following in relation to slugs in field crops:

Slugs are a complicated problem because most general insecticides don’t work well on them.
Sluggo Professional (PCP#30025) is registered for slugs in field crops. It is a bait, which must be consumed by the slugs to be effective but it could be expensive on a large field.
Often insecticides don’t work well on slugs and it may be related to the mucous coating slugs exude.
Be wary, if an insecticide is applied, the product will likely not affect the slugs but it will kill the ground beetles and other natural enemies that prey upon or parasitize slugs and could exacerbate the slug problem.
Growers using no-till or minimum till operations may consider tillage to help reduce future levels of slugs.

Health Canada has an overview of snails relating to gardening posted here.

Wanted – Slugs in field crops

This year, wet field conditions contributed to slug issues in cereals and canola. Researchers based at the University of Alberta are seeking live slug samples from field crops. Please take note of their collection protocol and help, if possible please!

Reminder – Feeding channels on the upper surfaces of the flag leaf in wheat were reported and evening scouting revealed the culprit!

Field scouting was performed in the evening from 8:30-10:30pm. As the temperatures decreased, the slugs moved up the wheat stems, climbing to the topside of the flag leaf and onto the wheat heads although they did not appear to feed at the developing kernels. Wheat was hand-collected by clipping stems ~20cm above the ground to later reveal a density of 1.04 slugs per stem (n=465 stems) causing the above damage (Fig. 2).

Thanks to Dr. John Gavloski (Manitoba Agriculture) who prepared the following in relation to slugs in field crops:

Slugs are a complicated problem because most general insecticides don’t work well on them.
Sluggo Professional (PCP#30025) is registered for slugs in field crops. It is a bait, which must be consumed by the slugs to be effective but it could be expensive on a large field.
Often insecticides don’t work well on slugs and it may be related to the mucous coating slugs exude.
Be wary, if an insecticide is applied, the product will likely not affect the slugs but it will kill the ground beetles and other natural enemies that prey upon or parasitize slugs and could exacerbate the slug problem.
Growers using no-till or minimum till operations may consider tillage to help reduce future levels of slugs.

Health Canada has an overview of snails relating to gardening posted here.

Wheat midge

Wheat Midge (Sitodiplosis mosellana) – Reminder – Based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK this season. Dry conditions in May and June have resulted in reduced emergence of adult populations across most of SK.

Review last week’s predictive model update (Wk 16) regarding the development for this pest. This week, the percent of adult emergence is depicted across the Canadian prairies as of July 28, 2019 (Fig. 1). The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil. Midge emergence is 100% complete in areas highlighted red, 90% complete in areas highlighted orange, and ≤50% in areas highlighted light orange or yellow (Fig. 1).

Monitoring:
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.

Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.

Inspect the developing kernels for the presence of larvae and the larval damage.

Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10). Check that post for help with in-field scouting for this economic pest of wheat! The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11). Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.

Wheat midge

Wheat Midge (Sitodiplosis mosellana) – Dry conditions in May and June have resulted in reduced emergence of adult populations across most of SK. Oviposition is well underway and larvae should be developing in wheat heads. Where wheat midge are present, the following maps indicate potential occurrence of eggs (Fig. 1) and larvae (present in wheat heads) across the prairies (Fig. 2). It should be noted that, based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK.

Monitoring:
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

Inspect the developing kernels for the presence of larvae and the larval damage.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.