Welcome to Week 11 for the 2025 growing season! This week includes: • Weather synopsis • Predicted grasshopper development • Predicted wheat midge development • Bertha armyworm • Aphids in field crops • Lygus bug monitoring • Cabbage seedpod weevil • Leaf miner on barley and wheat • Wheat stem sawfly • Predicted diamondback moth development • Canola flower midge • Provincial insect pest report links • Crop report links • Previous posts
Catch Monday’s Insect of the Weekfor Week 11 – This year features lesser-known insect pest species to help producers remain vigilant! Learn more about the Western Bean Cutworm!
Questions or problems accessing the contents of this Weekly Update? Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.
Dylan Sjolie, Tamara Rounce, Meghan Vankosky and Jennifer Otani
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Week 11
The seven-day average temperature across the Canadian prairies was ~18 °C between July 7-13, 2025 (Fig. 1), and approximately 1.5 °C warmer than the long-term climate normal (Fig. 3). Much of western Canada experienced temperatures above 16 °C except for the growing area near Grande Prairie AB. Over the past 30 days, eastern Manitoba was the warmest and the Peace River region was the coolest (Fig. 2). As the growing season progresses, average temperatures across the Canadian prairies continues to be slightly above the long-term climate normal (Fig. 3).
Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for July 7-13, 2025.Figure 2. Thirty-day average temperature (°C) observed across the Canadian prairies for the period of June 14-July 13, 2025.Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1-July 13, 2025.
It was another dry week for the majority of the Prairies outside of a few areas as the average cumulative rainfall was ~5 mm (Fig. 4; July 7-13, 2025). Over the past 30 days, areas surrounding Edmonton, Calgary, Lethbridge, and Saskatoon received the greatest rainfall, whereas northwest Manitoba and the Peace River region received the least precipitation (Fig. 5). So far this growing season, most growing regions across western Canada have received only about half of the long-term climate normal rainfall (Fig. 6).
Figure 4. Seven-day average precipitation (mm) observed across the Canadian prairies for the period of July 7-13, 2025.Figure 5. Thirty-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 14-July 13, 2025.Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1-July 13, 2025.
Dylan Sjolie, Tamara Rounce, Meghan Vankosky and Jennifer Otani
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Week 11
The grasshopper model was developed for the migratory grasshopper, but closely represents the development of the other primary pest grasshopper species found in the prairie region. The model uses weather from the current growing season to estimate the current status of grasshopper populations, but keep in mind that grasshoppers might not be present in all parts of the prairie region. Field scouting is imperative; the model estimates can be used to help time scouting activities.
The phenology model for grasshopper development on the Canadian prairies is based on: Olfert, O., R.M. Weiss, D. Giffen, M.A. Vankosky. 2021. Modelling ecological dynamics of a major agricultural pest insect (Melanoplus sanguinipes; Orthoptera: Acrididae): a cohort-based approach incorporating the effects of weather on grasshopper development and abundance. Journal of Economic Entomology 114: 122-130. DOI: 10.1093/jee/toaa254
As of July 13, 2025, model simulations were used to estimate development of grasshoppers predict that populations, where present, primarily consist of 4th and 5th instar nymphs (Fig. 1). These modelled estimates correspond with field observations made between Saskatoon and Rosetown, Saskatchewan, on July 11, 2025. As of July 13, 2025, model outputs estimate that adult grasshoppers should be present in fields near Winnipeg and between Lethbridge and Swift Current (Fig. 2).
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as the percent of the population reaching fifth instar stage, across the Canadian prairies, as of July 13, 2025.Figure 2. Predicted grasshopper (Melanoplus sanguinipes) development, presented as the percent of the population reaching adult stage, across the Canadian prairies, as of July 13, 2025.
Grasshopper Scouting Tips: ● Review grasshopper diversity and photos of nymphs, adults, and non-grasshopper species (Gavloski, Williams, Underwood, Johnson, Otani) to aid with field scouting from egg hatch and onwards. The PDF includes photos to help differentiate native versus pest grasshopper species plus froghopper, treehopper or even katydid species. ● It is best to scout on warm days when grasshopper nymphs are more active and easier to observe. ● Carefully check roadside ditches and along field edges but also check the edge of the crop and into the actual field. ● Younger or earlier instar nymphs are easier to manage – visit sites every few days to stay on top of local field conditions. ● A sweep-net can ‘detect’ grasshopper nymphs, however, economic thresholds for grasshoppers are based on the number of grasshoppers per square-metre counts. ● 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.
Important – A preliminary summary of available thresholds for grasshoppers has been kindly shared by Dr. J. Tansey (Saskatchewan Agriculture) in Table 1. When scouting, compare in-field counts to the available threshold value for the appropriate host crop AND for field or ditch situations. Available thresholds (nominal and economic) help support producers while protecting beneficials (i.e., predators, parasitoids, and pathogens) that regulate natural populations of grasshoppers.
Dylan Sjolie, Tamara Rounce, Meghan Vankosky and Jennifer Otani
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Week 11
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.
The model used to predict wheat midge development during the growing season was developed and is described in a published scientific paper: Olfert, O., R.M. Weiss, M. Vankosky, S. Hartley, J.F. Doane. 2020. Modelling the tri-trophic population dynamics of a host crop (Triticum aestivum; Poaceae), a major pest insect (Sitodiplosis mosellana; Diptera: Cecidomyiidae), and a parasitoid of the pest species (Macroglenes penetrans; Hymenoptera: Pteromalidae): a cohort-based approach incorporating the effects of weather. The Canadian Entomologist 152: 311-329. DOI: 10.4039/tce.2020.17
As of July 13, 2025, model simulations used to predict wheat midge development estimate that, where present, populations are primarily at the egg stage except in areas where the rainfall threshold was not met until mid-June. Large areas in Alberta, southern Saskatchewan, and Manitoba should have wheat midge adults laying eggs on wheat heads (Fig. 1). Other areas (north of Edmonton, Peace River, and surrounding Saskatoon) should still have populations entering the pupal stage (Fig. 2). Wheat fields along the south of the Manitoba-Saskatchewan border and surrounding Lethbridge may have larvae emerging in the wheat heads.
Figure 1. Percent of wheat midge larval population (Sitodiplosis mosellana) predicted to be in the pupal stage across western Canada, as of July 13, 2025.Figure 2. Percent of wheat midge larval population (Sitodiplosis mosellana) predicted to be in the egg stage across western Canada, as of July 13, 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!
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.
The phenology model for bertha armyworm development on the Canadian prairies was developed by Ross Weiss and Owen Olfert. Model simulations used to estimate development of bertha armyworm are now complete for the 2025 growing season. Now, in-field scouting for larvae is important!
Figure 1 includes photos of the various life stages of the bertha armyworm. There is one generation per year and pupae overwinter in the soil (Fig. 1, C). Each growing season, green unitraps utilizing pheromone lures are deployed and checked weekly over a 6-week window. Cumulative counts generated from the pheromone traps are used to estimate subsequent bertha armyworm densities. The cumulative moth count data is compiled using geospatial maps then posted to support and time in-field scouting for damaging populations of larvae by mid-July through to August.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2025. For example, Manitoba Agriculture’s June 19th Crop Pest Report includes Figure 2 with a reminder that other moth species are actively flying now so examine wing colourations and patterning carefully when checking the contents of bertha armyworm pheromone traps! Clover cutworm can be common by-catch in pheromone traps designed to monitor bertha armyworm, but also those designed to monitor true armyworm.
Figure 2. Comparison of diagnostic wing features of three moth species. Images and information all courtesy of Manitoba Agriculture, J. Gavloski who originally included in the June 19, 2025, issue of the Manitoba Crop Pest Update.
Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018), accessible as a free downloadable PDF in either English or French on our Field Guides page. Also consider reviewing this 2019 Insect of the Week featuring bertha armyworm and its doppelganger, the clover cutworm!
Aphid populations can quickly increase at this point in the season and particularly when growing conditions are warm and dry. This week, we share photos taken by B. DeSmet (Dirt Road Agronomy) with excellent examples of pea aphids in a field of peas (Fig. 1) and two general arthropod predators (Fig. 2) – some excellent photography!
Figure 1. Pea aphid adults and nymphs (each 2-3 mm long) feeding on field peas growing near Rycroft AB on July 11, 2025. Photos: B. DeSmet (Dirt Road Agronomy).
Figure 2. Several species of general arthropod predators consume multiple species of aphids; the green syrphid larva (left) and ladybug adult (right) are voracious predators of pea aphids in this pea field growing near Rycroft AB on July 14, 2025. Photos: B. DeSmet (Dirt Road Agronomy).
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)
Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.
Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps.In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.
Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Scouting tips to keep in mind: Begin monitoring canola when it bolts and continues until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs.
Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol. Also refer to the Lygus pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes Lygus bugs. The Flax Council of Canada includes Lygus bugs in their Insect Pest downloadable PDF chapter plus the Saskatchewan Pulse Growers summarize Lygus bugs in faba beans.
There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (Fig. 1; left photo). Mating and oviposition are quickly followed by eggs hatching within developing canola pods (Fig. 1; right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.
Figure 1. Cabbage seedpod weevil (left) and egg dissected from within a canola pod (right). Photos: the late Dr. Lloyd Dosdall.
Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (Fig. 1; right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically, a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.
There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (Fig. 2; left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod (Fig. 2; right photo, lower pod), feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole (Fig. 2; right photo, upper pod) from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season, these new adults migrate to overwintering sites beyond the field.
Figure 2. Larva feeding amongst developing seeds within canola pod (left) and larval entrance hole (right photo, lower pod) compared to mature larval exit hole (right photo, uppower pod). Photos: the late Dr. Lloyd Dosdall.
In-Field Monitoring:
Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.
This week, there were reports of leaf miner in multiple wheat and barley fields in Saskatchewan. While none not appear to involve economic injury levels, photos of the larval feeding damage were provided by Dr. J. Tansey (Saskatchewan Agriculture) in Figure 1.
Figure 1. Leaf miner larva and feeding damage in barley growing in Saskatchewan this week (July 17, 2025). Photos: J. Tansey (Saskatchewan Agriculture).
Field observations, coupled with available literature, suggest this leaf miner is Cerodontha lateralis (Diptera: Agromyzidae). C. lateralis was recorded in the 1920’s across North America and notably within Saskatchewan so this is not a new pest species. In addition to North America, C. lateralis also occurs in Japan and Europe. Interestingly, C. lateralis is rarely a pest in Europe owing to high rates of parasitism. Previous field collections in Alberta in 2007 and subsequent rearing revealed two species of parasitoid wasps (i.e., Closterocerus albipes and Closterocerus diastatae) emerged from C. lateralis puparia.
C. lateralis are known to utilize Avena, Elymus, Hordeum, Triticum, Agropyron, and Zea species as host plants.
Native to North America, the wheat stem sawfly is an economic pest depending on spring and durum wheat as its main crop hosts. These insects also target winter wheat, rye, grain corn and barley, in addition to feeding on native grass species. It is interesting to note that wheat stem sawflies do not feed on oat crops, as oats are toxic to wheat stem sawfly.
An adult wheat stem sawfly. Picture by Dylan Sjolie, AAFC-Saskatoon.
Wheat stem sawfly larvae feed on pith inside the stems of their host plant. Their feeding activity affects crop yield and quality. As infested host plants mature, the larvae travel down the stem to its base, where “V” shaped notches are cut into the stem a little above ground level. These notches leave plants vulnerable to collapsing or lodging, especially during wind events. Because wheat stem sawflies also breed and develop on native grass species, economic damage tends to be most prevalent around crop margins where native and agricultural plants are found close together.
An adult wheat stem sawfly. Picture by Dylan Sjolie, AAFC-Saskatoon.
Adult wheat stem sawflies are 8–13 mm long with a wasp-like resemblance, due to their black body and yellow legs. Females have an egg-laying organ (an ovipositor) that extends from their abdomen. When resting on plant stems, these insects will point their heads downward. Mature larvae are 13 mm long and resemble whitish worms with brown heads.
Biological and monitoring information related to wheat stem sawflies in field crops can be found on our Monitoring Protocols page as well as on provincial Agriculture Ministry pages (Manitoba, Saskatchewan and Alberta).
Dylan Sjolie, Tamara Rounce, Meghan Vankosky and Jennifer Otani
Categories
Week 11
Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Each spring, adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season.
Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths (Fig. 1) attracted to pheromone-baited delta traps deployed in fields. Weekly trap interceptions are observed to generate cumulative counts. These cumulative count estimates are broadly categorized to help producers prioritize and time in-field scouting for larvae.
Figure 1. Adult diamondback moth.
Diamondback moths were captured on pheromone traps across western Canada from mid- to late-May in 2025. Once adults arrive, there can be several in-season, non-migrant generations of diamondback moth developing throughout the remainder of the growing season. Warm, dry weather tends to promote rapid development of high-density populations of larvae capable of causing severe damage to host crops, including canola.
The model for diamondback moth development on the prairies was developed by Ross Weiss and Owen Olfert. Model simulations were used to estimate the number of non-migrant generations of diamondback moth (Plutella xylostella).
As of July 13, 2025, model outputs suggest that diamondback moth populations are primarily in the second non-migrant generation across the Prairie except for areas within the Peace River region (Fig. 2).
Figure 2. Predicted number of in-season generations of diamondback moth (Plutella xylostella) expected to have developed across the Canadian prairies, as of July 13, 2025.
Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2025.
In-Field Monitoring:Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 3) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.
Figure 3. Diamondback larva measuring ~8mm long. Note brown head capsule and forked appearance of prolegs on posterior.
The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m² (approximately 2-3 larvae per plant). Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).
Figure 4. Diamondback moth pupa within silken cocoon.
Scouting for canola flower midge tends to be easiest as the flowering stage of canola ends and pod development begins. Female canola flower midge lay eggs on developing canola buds and larvae develop inside the buds, resulting in galled flowers that do not open or produce pods.
Although canola flower midge does not appear to occur at densities that cause economic damage, scouting for canola flower midge will help to monitor population growth at the local scale to avoid surprises in the future. The monitoring protocol used during our survey from 2017-2019 is now available online so that everyone can scout for canola flower midge.
Check out the Canola Flower Midge Scouting post from Week 10 in 2023 for pictures of damage caused by this insect and to see a map of canola flower midge distribution.
Jennifer Otani, James Tansey, John Gavloski, Carter Peru, Shelley Barkley and Amanda Jorgensen
Categories
Week 11
Prairie-wide provincial entomologists provide insect pest updates throughout the growing season. Follow the hyperlinks to access their information as the growing season progresses:
MANITOBA’SCrop Pest Updates for 2025 are available! Review a PDF copy of the latest reports released July 17, 2025! • Insect pests named in the July 17th report include aphids (on soybeans, peas, small grain cereals), armyworms, and wheat stem maggots. • Cumulative 2025 counts of intercepted diamondback moths are updated weekly to provide regional information to producers and guide in-field scouting. There are multiple areas with cumulative moth catches categorized at “elevated risk” and three areas categorized as “higher level”. • Pheromone-baited trap counts are available for true armyworms in these reports. • Cumulative 2025 counts of intercepted bertha armyworm moths are updated weekly. There are three areas where cumulative moth counts are categorized as “uncertain risk” so far. • Bookmark the Crop Pest Update Index and the insect pest homepage to access fact sheets and more!
SASKATCHEWAN’SInsect pest homepage links to important information! Thank you to Dr. J. Tansey who provided the following overview (as of July 17, 2025): • Bertha armyworm pheromone trap counts are reaching levels that warrant in-field scouting for larvae now. • Diamondback moth pheromone trap counts remain low but continue to scout for larvae. • Multiple reports relaying barley thrips on durum but crop is heading so yields should not be affected. Most reports involve numbers below but approaching the threshold of ~8 thrips per stem although densities exceeded 14 per stem (wheat threshold described in a Greek study). • Near Swift Current (July 16, 2025), grasshopper densities were low with primarily migratory plus some Packard’s grasshoppers observed. The migratory grasshoppers were dominated by adult stages, however, Packard’s grasshoppers were at 4th instar stage or younger. No striped grasshopper were encountered. • Received some reports of inadequate control of pea aphid using a foliar insecticide in lentils so following up with test kits. Please contact the Ministry, if you see similar issues with pea aphid control. • Received a report from an agronomist reporting 50-80% infestation of lower pods with cabbage seedpod weevil larvae in multiple unsprayed fields. Also observed that the weevil is less numerous in late-seeded crops. • Confirmed black vine weevil (Otiorhynchus sulcatu) in a greenhouse near Regina. The species is present in eastern Canada but this is only the second account in SK. It is a large, flightless weevil, black with orange tufts on the fused elytra. Normally it is a nursery and greenhouse issue. There are registered control products.
ALBERTA’SInsect Pest Monitoring Network webpage links to insect survey maps, live feed maps, insect trap set-up videos, and more. There is also a Major Crops Insect webpage. Remember Agri-News includes insect-related information: • July 14, 2025, issue includes a segment advising producers to “be on the lookout for cabbage seedpod weevil”. • Diamondback moth pheromone trap live monitoring map for AB – Cumulative counts derived from weekly data are now available the Live map. • Bertha armyworm pheromone trap live monitoring map for AB – Cumulative counts derived from weekly data are available on the Live map. • Cabbage seedpod weevil live sweep-net monitoring map for AB – In-field reports are uploaded daily so refer to the Live map. • Wheat midge live sweep-net monitoring map for AB – Cumulative counts derived from weekly data are available on the Live map.
