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.
Last week (July 8-14, 2024), average cumulative 7 day rainfall was 5 mm (Figure 1) and was well below the previous week (July 1-7) that experienced an average cumulative rainfall value of 16.7 mm. The average 30 day (June 14 – July 14) temperature was 0.5° C warmer than long term average values. Most of the prairies reported 30 day rainfall amounts ranging from normal to above normal. A region from Saskatoon to Oyen has had uncharacteristically high rainfall; Kindersley and Oyen had greater than 250 % of normal precipitation (Figure 2). Driest conditions were observed near Edmonton and the western areas of the Peace River region. Since April 1, the 2024 growing season average temperatures have been 0.5° C greater than climate normal values. Most of the prairies have had above normal to above normal (157 %) rainfall (Figure 3).
Figure 1. 7 day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 8-14, 2024.Figure 2. 30 day percent of normal rain (%) observed across the Canadian prairies for the period of June 14-July 14, 2024. Figure 3. Growing season percent of normal rain %) observed across the Canadian prairies for the period of April 1 – July 14, 2024.
Soil moisture conditions (top 5 cm) continue to be driest for the eastern and Peace River regions of Alberta and southern regions of Saskatchewan (Figure 4). Soil moisture values were greatest for Manitoba and the Parkland region of Saskatchewan.
Figure 4. 7 day average saturated soil moisture (% soil moisture for the surface layer, <5 cm depth) for the period of July 8-14, 2024.
Relative to climate normal values, average temperatures have increased over the past four weeks. The 7 day average temperature for July 14-20, 2024 was 20.5 °C and was 3.3 °C warmer than normal. Warmest temperatures were observed for northern regions of the Alberta Peace River region, eastern regions of Alberta, and southern regions of Saskatchewan (Figure 1).
Figure 1. Seven day average temperature (°C) observed across the Canadian prairies for the period of July 14-20, 2024.
The 30 day (June 21-July 20) average temperature (18.4 °C) was 2 °C warmer than average (Figure 2). Growing season (April 1 – July 20) average temperatures were 0.7 °C warmer than average (Figures 3 and 4, respectively).
Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of June 21 – July 20, 2024.Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – July 20, 2024.Figure 4. Growing season average temperature anomalies (°C) observed across the Canadian prairies for the period of April 1 – July 20, 2024.
Last week (July 14-20, 2024) average cumulative 7 day rainfall was 4.4 mm (Figure 5). Most of the prairies reported 30 day rainfall amounts that were normal to above normal (Figure 6). Rainfall amounts have been above normal for the majority of Manitoba and normal to below normal for most of Alberta. Driest conditions were observed near Edmonton and the western areas of the Peace River region. Rainfall values (June 21-July 20) have been highly variable across Saskatchewan. Growing season (April 1 – July 20) precipitation has been above normal to above normal (147 %) rain (Figure 7).
Figure 5. 7 day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 14-20, 2024.Figure 6. 30 day percent of normal rain (%) observed across the Canadian prairies for the period of June 21 – July 20, 2024.Figure 7. Growing season percent of normal rain (%) observed across the Canadian prairies for the period of April 1 – July 20, 2024.
Soil moisture conditions (top 5 cm) continue to be driest for eastern and Peace River regions of Alberta and southern regions of Saskatchewan (Figure 8). Soil moisture values were greatest for Manitoba and the Parkland region of Saskatchewan.
Figure 8. 7 day average saturated soil moisture (%) for the surface layer (<5cm)) for the period of July 14-20, 2024.
Aphid populations can quickly increase at this point in the season and particularly when growing conditions are warm and dry. Access the Provincial Insect Pest Report for Wk12 to remain alert to areas and crops suffering from aphid pest pressure.
Figure 1. Pea aphid adults (each 3-4 mm long) and nymph. Photo: M. Dolinski.
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)
Scouting for canola flower midge tends to be easiest as the flowering stage of canola ends and pod development begins. Female canola flower midge lay eggs on developing canola buds and larvae develop inside the buds, resulting in galled flowers that do not open or produce pods.
Although canola flower midge does not appear to occur at densities that cause economic damage, scouting for canola flower midge will help to monitor population growth at the local scale to avoid surprises in the future. The monitoring protocol used during our survey from 2017-2019 is now available online so that everyone can scout for canola flower midge.
Check out the Canola Flower Midge Scouting post from Week 10 in 2023 for pictures of damage caused by this insect and to see a map of canola flower midge distribution.
Compare canola flower midge damage to the closely related Swede midge which was featured as Wk12’s Insect of the Week.
Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.
Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies. Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre2! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of the diamondback moth.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
The economic threshold for immature and flowering canola is 100-150 larvae per metre2.
Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.
On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally.
Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.
Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps.In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.
Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Scouting tips to keep in mind: Begin monitoring canola when it bolts and continues until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
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.
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. ● 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.
Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.
Prairie-wide provincial entomologists provide insect pest updates throughout the growing season. Follow the hyperlinks to readily access their information as the growing season progresses:
MANITOBA’SCrop Pest Updates for 2024 are available. Access the online July 25, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include: • Aphids – Dr. J. Gavloski reported that, “Pea aphids in peas” remained a concern that resulted in “some control in the Southwest, Central and Interlake regions”. Additionally, “aphids in cereal crops are becoming more noticeable in some areas” but there also were “reports of aphid mummies (parasitized aphids), lacewings and lots of lady beetles in some fields of wheat.” • True armyworm – “True armyworms were still noted in forage grasses in the Central and Interlake regions. There were no reports of control of true armyworms over the past week, and levels of larvae may be declining as they turn to pupae. Review the cumulative pheromone trap counts in the July 24, 2024 report. Also find reports of natural enemies of armyworm in this report. • Grasshoppers– Reports that, “grasshoppers are more noticeable in crops in some areas, while in other areas grasshopper activity is mainly limited to field edges or is of less concern. There was a report of a number of dead grasshoppers clinging to the top of wheat heads (a sign of a fungal pathogen) in the Southwest region.” • Canola flower midge – “Unopened buds, a result of canola flower midge, is noticeable in some canola fields in the Northwest region.” • European corn borer – Review the report for tips to scout for egg masses in corn, hemp, quinoa, potatoes and other host crops. Access both the updated fact sheet and request to report by downloading and using the free Survey123 App. • Corn rootworm – Review the report for tips to scout for both the northern and western corn rootworm. • Bertha armyworm pheromone trap monitoring – Reports moths in “79 of 82 traps” although “counts have been low so far”. So far, the highest cumulative count reported is “290 from a trap near Killarney in the Southwest region”. Access the PDF copy of the July 25 report. • Diamondback moth pheromone trap monitoring – Trapping is complete for 2024 (as of Wk 09; access the PDF copy of the July 4 report).
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, AAI’s Agri-News occasionally includes insect-related information, e.g., assessing and a description of missing pods on canola (July 22, 2024), scout for wheat midge (July 15, 2024), the right canola crop stage to spray for lygus bugs (July 8, 2024), soil moisture, wheat midge and other insect pests (June 24, 2024), scout for grasshoppers and other insect pests (June 17, 2024); how to manage stem feeding from flea beetles, keep canola bins malathion-free, scout for grasshoppers and other pests (June 10, 2024); scout for insect pests (June 3, 2024); scout for grasshoppers (May 27, 2024); flea beetle control (May 6, 2024); cereal insect pests, latest on insects in canola, and post-emergence wireworm scouting (May 13, 2024). • Wheat midge monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts from 37 trap locations are reporting; 10 sites in central Alberta are “high” and in the Peace River region 22 sites are reporting “high”, 2 sites are “medium”, and 2 sites are “low” (as of July 25, 2024). • Cabbage seedpod weevil monitoring – Sweep-net count data can be reported here then the data populates the Live Map. So far, a total of 16 sites in southern Alberta are reporting; there are 14 “low risk” plus 2 “high risk” reports as of July 18, 2024). • Bertha armyworm pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts from 266 trap locations are all reporting “low risk” across the province while 1 trap location near Fairview, plus 3 trap locations in southern Alberta (2 in Vulcan County plus 1 near Lethbridge) are reporting “medium risk” as of July 25, 2024). • Diamondback moth pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts have been recorded from 32 reporting sites and 28 remain in the “no risk” category as of July 4, 2024). Four trap locations have caught > 25 adult diamondback moths; sites fall within the County of Grande Prairie (as of June 8, 2024), County of Warner (as of June 15, 2024), Vulcan County (as of June 15, 2024), and County of Barrhead (as of June 15, 2024). • Cutworm live monitoring map – Cumulative counts arising from weekly data are available so refer to the Live Map. 10 surveyed sites have reported from across the province, nine falling within southern Alberta and one report from the County of Grande Prairie.
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.
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.
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.
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. ● 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.
Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre2! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of the diamondback moth.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
The economic threshold for immature and flowering canola is 100-150 larvae per metre2.
Access the Provincial Insect Pest Report for Wk11 for updates for this economic insect pest.
Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies. Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
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:
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.
Figure 1. European skipper (Thymelicus lineola) adults on timothy seed seeds. Photo: S. Dufton, AAFC-Beaverlodge.
There is one generation per year of European skipper but butterfly oviposition or egg laying largely dictates where damage occurs the following summer. 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).
On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally.
Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.
Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps.In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.
Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Scouting tips to keep in mind: Begin monitoring canola when it bolts and continues until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
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.
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.
Prairie-wide provincial entomologists provide insect pest updates throughout the growing season. Follow the hyperlinks to readily access their information as the growing season progresses:
MANITOBA’SCrop Pest Updates for 2024 are available. Access the online July 18, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include: • Aphids – Dr. J. Gavloski reported, “control of aphids in field peas from the Southwest (Boissevain area), and Central region (Notre Dame de Lourdes, Starbuck and Fannystelle areas)”. Access the Aphids on Peas fact sheet. • True armyworm – Reports that, “true armyworms remain at high levels in some areas, and control was reported from the Interlake and Central regions. There is also some evidence of parasitism of true armyworms starting to become visible (pupal clusters of a parasitic wasp called Cotesia).” Access the PDF copy of the July 10 report. • Grasshoppers– Reports, “some grasshopper control in soybeans and cereal crops occurred in the Central region”. • Sunflower bud moth – “Has been noticeable in many sunflower fields” and is featured in the July 18th report. • Bertha armyworm pheromone trap monitoring – Reports moths in “66 of 79 traps” although “counts have been low so far”. Where present, “eggs are now starting to hatch”. Access the PDF copy of the July 10 report. • Diamondback moth pheromone trap monitoring – Trapping is complete for 2024 (as of Wk 09; access the PDF copy of the July 4 report).
SASKATCHEWAN’SCrop Production News is back for the 2024 growing season! Access the online Issue #4 report which includes sections covering thrips in small grains cereal crops, cabbage seedpod weevil, and mid-season gopher control. Bookmark their insect pest homepage to access important information! • Insect pests to watch – A brief summary of the week was provided by Dr. J. Tansey (as of July 17) – “The prevalent story this week was pea aphid in lentils. Diamondback moth larvae were numerous in a smattering of fields in the southwest and monitoring is warranted. A few pockets of grasshoppers remain in southwest and east-central regions of Saskatchewan and populations of two-striped are reaching adulthood this week.” • Diamondback moth – Pheromone trapping is complete for 2024 and can be reviewed online. A total of 24 sites intercepted a cumulative total of ≥25 moths so in-field monitoring for larvae should be prioritized in those areas. • Bertha armyworm – Cumulative catches in phermone-baited unitraps “continue to increase slowly with one trap in east central reporting more than 300”. • Also access the Crops Blog Posts that released a grasshopper activity update (June 2024), announced registration for the Crop Diagnostic School 2024 but also posts help for scouting fields for wireworms (May 2024), grasshopper identification: pest or not (Apr 2024), a summary of wheat midge populations and management (Mar 2024), and a description of pea leaf weevil populations (Feb 2024).
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, AAF’s Agri-News occasionally includes insect-related information, e.g., scout for wheat midge (July 15, 2024), the right canola crop stage to spray for lygus bugs (July 8, 2024), soil moisture, wheat midge and other insect pests (June 24, 2024), scout for grasshoppers and other insect pests (June 17, 2024); how to manage stem feeding from flea beetles, keep canola bins malathion-free, scout for grasshoppers and other pests (June 10, 2024); scout for insect pests (June 3, 2024); scout for grasshoppers (May 27, 2024); flea beetle control (May 6, 2024); cereal insect pests, latest on insects in canola, and post-emergence wireworm scouting (May 13, 2024). • Wheat midge monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Shelley Barkley reported that, “midge numbers are increasing in the Edmonton and Peace region”. So far, cumulative trap counts from 35 trap locations are reporting; 10 sites in central Alberta are “high” and in the Peace River region 21 sites are reporting “high”, 2 sites are “medium”, and 2 sites are “low” (as of July 18, 2024). • Cabbage seedpod weevil monitoring – Sweep-net count data can be reported here then the data populates the Live Map. So far, a total of 16 sites in southern Alberta are reporting; there are 14 “low risk” plus 2 “high risk” reports as of July 18, 2024). • Bertha armyworm pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts from 265 trap locations are all reporting “low risk” while 1 trap location near Vulcan plus 1 trap location near Lethbridge are both reporting “medium risk” as of July 18, 2024). • Diamondback moth pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts have been recorded from 32 reporting sites and 28 remain in the “no risk” category as of July 4, 2024). Four trap locations have caught > 25 adult diamondback moths; sites fall within the County of Grande Prairie (as of June 8, 2024), County of Warner (as of June 15, 2024), Vulcan County (as of June 15, 2024), and County of Barrhead (as of June 15, 2024). • Cutworm live monitoring map – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, 10 surveyed sites have reported from across the province, nine falling within southern Alberta and one report from the County of Grande Prairie.
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.
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. Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
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.
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.
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. ● 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.
Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre2! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of the diamondback moth.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
The economic threshold for immature and flowering canola is 100-150 larvae per metre2.
Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo). Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.
Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.
There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season, these new adults migrate to overwintering sites beyond the field.
Monitoring:
Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.
Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below for reference; retrieved 2024Jul04).
Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies. Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
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).
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.
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).
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.
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.
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. Access the Provincial Insect Pest Report for Wk09 for updates.
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.
This week, European skipper was reported in the northeast of Saskatchewan where more forage crops are grown.
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.
Figure 1. European skipper (Thymelicus lineola) adults on timothy seed seeds. Photo: S. Dufton, AAFC-Beaverlodge.
There is one generation per year of European skipper but butterfly oviposition or egg laying largely dictates where damage occurs the following summer. 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).
Track the migration of the Monarch butterflies as they move north by checking the 2024 Monarch Migration Map! A screenshot of Journey North’s “first sightings of adults” map was featured Wk07. This week, the updated map of “first sightings of LARVAE” has been placed below (retrieved 11Jul2024) but follow the hyperlink to check the interactive map. Larvae have been spotted in Manitoba and now Saskatchewan!
Prairie-wide provincial entomologists provide insect pest updates throughout the growing season. Follow the hyperlinks to readily access their information as the growing season progresses:
MANITOBA’SCrop Pest Updates for 2024 are available. Access the online July 11, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include: • Pea aphids – Dr. J. Gavloski reported, “high levels of pea aphids in peas from fields in the Norte Dame de Lourdes area of the Central region, and the Hamiota / Oak River area of the Southwest regions”. The report includes the economic threshold for pea aphids to be checked at the beginning of flowering for field peas. • True armyworm in MB – Reports, true armyworms in some forage grass fields in the Interlake requiring insecticide treatments”. The highest cumulative trap count so far is 435 from a trap near Riverton in the Interlake region.” Scouting for larvae in cereals and forage grasses is still recommended in areas of the Central, Eastern, and Interlake regions. Access the PDF copy of the July 10 report. • Grasshoppers– Reports, “high levels of grasshoppers in wheat in the Central and Northwest regions”. • Bertha armyworm pheromone trap monitoring – Reports moths in “66 of 79 traps” although “counts have been low so far”. Where present, “eggs are now starting to hatch”. Access the PDF copy of the July 10 report. • Diamondback moth pheromone trap monitoring – Trapping is complete for 2024 (as of Wk 09; access the PDF copy of the July 4 report).
SASKATCHEWAN’SCrop Production News is back for the 2024 growing season! Access the online Issue #4 report which includes sections covering thrips in small grains cereal crops, cabbage seedpod weevil, and mid-season gopher control. Bookmark their insect pest homepage to access important information! A brief summary of the week was provided by Dr. J. Tansey (as of July 10): • Insect pests to watch – “Diamondback moth were detected in several sites”. In canola, “some lygus were detected” but “significant cabbage seedpod weevil were observed near Swift Current”. There were “several reports of barley thrips in wheat and durum”. “Pea aphid were reported in pulses”. Also, “several sites in southern and central regions have suffered ground squirrel damage to canola” with “major sections completely cleaned off”. • Grasshopper nymphs – “Grasshopper pressures have diminished considerably”. • Diamondback moth – Pheromone trapping is complete for 2024 and can be reviewed online. A total of 24 sites intercepted a cumulative total of ≥25 moths so in-field monitoring for larvae should be prioritized in those areas. • Also access the Crops Blog Posts that released a grasshopper activity update, announced registration for the Crop Diagnostic School 2024 but also posts help for scouting fields for wireworms (May 2024), grasshopper identification: pest or not (Apr 2024), a summary of wheat midge populations and management (Mar 2024), and a description of pea leaf weevil populations (Feb 2024).
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, AAF’s Agri-News occasionally includes insect-related information, e.g., the right canola crop stage to spray for lygus bugs (July 8, 2024), soil moisture, wheat midge and other insect pests (June 24, 2024), scout for grasshoppers and other insect pests (June 17, 2024); how to manage stem feeding from flea beetles, keep canola bins malathion-free, scout for grasshoppers and other pests (June 10, 2024); scout for insect pests (June 3, 2024); scout for grasshoppers (May 27, 2024); flea beetle control (May 6, 2024); cereal insect pests, latest on insects in canola, and post-emergence wireworm scouting (May 13, 2024). • Wheat midge monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Shelley Barkley reported that, “midge numbers are increasing in the Edmonton and Peace region”. So far, cumulative trap counts from 26 trap locations are reporting; 6 sites in central Alberta are “high” and in the Peace River region 18 sites are reporting “high”, 2 sites are “medium”, and 2 sites are “low” (as of July 11, 2024). • Grasshoppers – Shelley Barkley reported that “nymphs are around but no adult pest grasshoppers have been seen yet” but that “(they) may be seen soon with the hot weather this week and expected for the next week or so”. • Cabbage seedpod weevil monitoring – Sweep-net count data can be reported here then populates the Live Map. So far, a total of 16 sites in southern Alberta are reporting; there are 14 “low risk” plus 2 “high risk” reports as of July 11, 2024). • Bertha armyworm pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts from 251 trap locations are all reporting “low risk” while 1 trap location near Vulcan is reporting “medium risk” as of July 11, 2024). • Armyworm moths – Shelley Barkley reported that, “Lindgren traps have been catching high numbers of armyworm moths (Miller moths) in the last week; in her experience, high moth numbers in traps in summer are indicative of high levels of cutworm damage the following spring”. • Diamondback moth pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts have been recorded from 32 reporting sites and 28 remain in the “no risk” category as of July 4, 2024). Four trap locations have caught > 25 adult diamondback moths; sites fall within the County of Grande Prairie (as of June 8, 2024), County of Warner (as of June 15, 2024), Vulcan County (as of June 15, 2024), and County of Barrhead (as of June 15, 2024). • Cutworm live monitoring map – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, 10 surveyed sites have reported from across the province, nine falling within southern Alberta and one report from the County of Grande Prairie.
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.
Last week (Jun 24-30, 2024), a number of locations had 7 day rainfall amounts that exceeded 50 mm. Most of the rain was observed across the central prairies extending from Oyen to Brandon. Beaverlodge and Grande Prairie had rain amounts that exceeded 45 mm. Growing season temperatures have been similar to climate normal values while rainfall amounts continue to be well above average. Manitoba continues to have warm temperatures and above normal precipitation.
The average 30 day temperature (June 1 – 30, 2024) was 13.9 °C and was almost 1 °C cooler than long term average temperatures. Warmest temperatures were observed across Manitoba and the southern prairies (Figure 1). Most of the prairies have reported 30 day rainfall amounts were normal to above normal. Average cumulative rainfall (mm) over the past 30 days was 86 mm (71 mm last week) and was 150 % of climate normal values. Rainfall amounts have been greatest for Manitoba as well as central and Parkland regions of Saskatchewan (Figure 2). Rain amounts for the area extending from Saskatoon to Kindersley has been 250 % of normal for the past 30 days while cumulative 30 day rain totals for southwestern Saskatchewan and southern Alberta have been less than 65 % of normal.
Figure 1. 30 day average temperature (°C) observed across the Canadian prairies for the period of June 1-30, 2024.Figure 2. 30 day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 1-30, 2024.
Since April 1, the 2024 growing season average temperature (10 °C) has been marginally greater than climate normal values. Warmest average temperatures were observed across a region extending from Winnipeg to Saskatoon and southwest to Lethbridge (Figure 3). Growing season rainfall (prairie wide average) was 194 mm and has been above normal across most of the prairies (Figure 4). Regions around Brandon and Saskatoon have been particularly wet. Near normal precipitation amounts occurred across southern Saskatchewan, western Alberta and western areas of the Peace River region. Current rain amounts have been 175 % of climate normals. Cumulative rainfall has been lowest for a large region than is west of a line that extends from Regina to Grande Prairie (Figure 5).
Figure 3. Growing season average temperature difference from climate normal (°C) observed across the Canadian prairies for the period of April 1 – June 30, 2024.Figure 4. Growing season percent of normal rain (%) observed across the Canadian prairies from April 1 to June 30, 2024.Figure 5. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – June 30, 2024.
Soil moisture conditions (top 5 cm) continue to be driest for western regions of Saskatchewan and eastern regions of Alberta (Figure 6) and is similar to the 30 day cumulative rainfall map (Figure 4). Soil moisture values were greatest for Manitoba and the Parkland region of Saskatchewan. Lowest values occurred across southern and central regions of Alberta as well as southwestern Alberta.
Figure 6. 7 day average saturated soil moisture (% soil moisture for the surface layer, <5 cm depth) for the period of June 24-30, 2024.
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.
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.
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.
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. ● 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.
Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.
Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre2! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of the diamondback moth.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo). Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.
Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.
There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season, these new adults migrate to overwintering sites beyond the field.
Monitoring:
Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.
Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below for reference; retrieved 2024Jul04).
The alfalfa weevil, Hypera postica, overwinters as an adult that typically flies to alfalfa fields in April and May. Adult females start to lay eggs in May. Adults consume alfalfa foliage, but typically do not cause economic levels of damage. However, larval feeding peaks in June and, if high densities are present, can cause yield losses. Thus, field scouting to assess larval stages and densities should begin in May through to June. Review the alfalfa weevil life cycle and the damage it causes.
Reminder – The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer” (Fig. 1). The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9 mm long. Alfalfa growers are encouraged to check the Alfalfa Weevil Monitoring Protocol prepared by Dr. Julie Soroka (AAFC-Saskatoon).
Figure 1. Alfalfa weevil injury to alfalfa; (a, b) leaf notching and skeletonizing and (c) injury to stem tips. Photos: AAFC-Soroka.
Economic Thresholds and Control: Economic thresholds for alfalfa weevil vary with the alfalfa crop type (whether hay or seed) the advising body, and the measurable unit. In hay fields, forage losses can be economic if one or more of the following symptoms are noted: • if 25-50 % of the leaves on the upper one-third of the stem show damage, or • if 50-70% of the terminals are injured, or • if 1 to 3 third or fourth instar larvae occur per stem (with shorter stems having lower economic thresholds and 3 or more larvae requiring treatment no matter what the alfalfa height), or • 20-30 larvae per sweep occur when 12 % leaf loss is acceptable. Early cutting of the first growth of alfalfa or insecticide treatment will reduce alfalfa weevil populations. If the hay crop value is high and weevil injury is seen or 2 or more larvae per stem reappear in regrowth after cutting, insecticide may be necessary if a second cut is anticipated. In alfalfa seed fields, economic thresholds are 20-25 third to fourth instar larvae per sweep or 35-50 % of the foliage tips showing damage. Thresholds increase with the height of the alfalfa, and decrease in drought conditions. Several small wasps parasitize alfalfa weevil larvae and adults, and in the past these natural control agents kept the weevil in check in most years. One of these wasps, Bathyplectes curculionis (Thomson), (Fig. 3a-c), parasitizes alfalfa weevil in Alberta and Saskatchewan, and is now found in Manitoba.
Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted 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.
Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies. Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
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).
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.
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).
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.
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.
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.
While the PPMN no longer predicts the development of Culex tarsalis, the vector for West Nile Virus(WNV), areas of the Canadian prairies in 2024 have received high levels of precipitation. This is noteworthy because the larvae of C. tarsalis can develop in, “agricultural tailwater, alkaline lake beds, fresh and saline wetlands, secondary treated sewage effluent and oil field run-off” (Centre for Vector Biology URL retrieved 2024Jul04).
Historically, by mid-July, C. tarsalis adults begin to fly in southern parts of the Canadian prairies. Field scouts and outdoor enthusiasts should wear DEET to protect against C. tarsalis and WNV.
Track the migration of the Monarch butterflies as they move north by checking the 2024 Monarch Migration Map! A screenshot of Journey North’s “first sightings of adults” map was featured Wk07. This week, the updated map of “first sightings of LARVAE” has been placed below (retrieved 04Jul2024) but follow the hyperlink to check the interactive map. Larvae have been spotted in Manitoba so far!
Prairie-wide provincial entomologists provide insect pest updates throughout the growing season. Follow the hyperlinks to readily access their information as the growing season progresses:
MANITOBA’SCrop Pest Updates for 2024 are available. Access the online July 4, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include: • Flea beetles – Dr. J. Gavloski reported, “some spraying for flea beetles in late-seeded fields over the past week”. • Alfalfa weevil – Was “at high levels in alfalfa and other forage legumes in some fields; there have been reports of high levels now from the Interlake, Eastern, Northwest and Southwest regions”. • Bertha armyworm pheromone trap monitoring – Reports moths in “58 of 79 traps” although “counts have been low so far”. Access the PDF copy of the July 4 report. • Diamondback moth pheromone trap monitoring – Reports that trapping is complete for 2024 with moths present “in 75 out of 92 traps” and that, “trap counts were generally been low in the Northwest and Southwest regions with a few traps in the Northwest exceeding 25 moths” and “some moderate to high counts in the Eastern, Central, and Interlake regions”. The highest cumulative trap count was 233 from a trap near Riverton in the Interlake region.” Access the PDF copy of the July 4 report. • True armyworm in MB – “Armyworms have been caught in 34 traps so far. Eighteen traps have intercepted >25 moths; three in the Central region, five in the Eastern region, and ten in the Interlake region. The highest cumulative trap count so far is 434 from a trap near Riverton in the Interlake region.” Scouting for larvae in cereals and forage grasses is still recommended in areas of the Central, Eastern, and Interlake regions. “Armyworm larvae have been reported in the Central and Interlake regions, with some control applied in the Interlake region”. Access the PDF copy of the July 3 report. • Features a description of the alfalfa weevil with a link to the fact sheet. • Advises of an emergency registration of Carbine in confection sunflowers in Manitoba from July 21, 2024 to July 20, 2025 to control lygus bugs.
SASKATCHEWAN’SCrop Production News is back for the 2024 growing season! Access the online Issue #3 report. Bookmark their insect pest homepage to access important information! A brief summary of the week was provided by Dr. J. Tansey (as of June 27): • Insect pests to watch – “Flea beetles were reported as minor to moderate issue throughout the province with spraying reported in NW and some serious issues reported from a small number of sites in SW”. There was “some minor root maggot damage reported in EC and NE” and “limited moderate wireworm problems in the SW and EC”. “Cutworm pressures were generally low but moderate pressures were reported in the SE”. More recently this week, “barley thrips activity” was reported. • Grasshopper nymphs – “Grasshopper issues were sporadic but moderate pressures were reported in central regions and limited severe pressure in SW.” • Diamondback moth – Cumulative count data from pheromone traps across the province is complete for 2024 and can be reviewed online. A total of 24 sites intercepted a cumulative total of ≥25 moths so in-field monitoring for larvae should be prioritized in those areas. • Also access the Crops Blog Posts that released a grasshopper activity update, announced registration for the Crop Diagnostic School 2024 but also posts help for scouting fields for wireworms (May 2024), grasshopper identification: pest or not (Apr 2024), a summary of wheat midge populations and management (Mar 2024), and a description of pea leaf weevil populations (Feb 2024).
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, AAF’s Agri-News occasionally includes insect-related information, e.g., soil moisture, wheat midge and other insect pests (June 24, 2024), scout for grasshoppers and other insect pests (June 17, 2024); how to manage stem feeding from flea beetles, keep canola bins malathion-free, scout for grasshoppers and other pests (June 10, 2024); scout for insect pests (June 3, 2024); scout for grasshoppers (May 27, 2024); flea beetle control (May 6, 2024); cereal insect pests, latest on insects in canola, and post-emergence wireworm scouting (May 13, 2024). • Wheat midge monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts from 6 trap locations are all reporting both “medium” and “high” risk as of July 4, 2024). • Cabbage seedpod weevil monitoring update for AB – Sweep-net count data can be reported here then populates the Live Map. So far, a total of 8 sites in southern Alberta are reporting; there are 6 “low risk” plus 2 “high risk” reports as of July 4, 2024). • Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts from 242 trap locations are all reporting “low risk” category as of July 4, 2024). • Diamondback moth pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts have been recorded from 32 reporting sites and 28 remain in the “no risk” category as of July 4, 2024). Four trap locations have caught > 25 adult diamondback moths; sites fall within the County of Grande Prairie (as of June 8, 2024), County of Warner (as of June 15, 2024), Vulcan County (as of June 15, 2024), and County of Barrhead (as of June 15, 2024). • Cutworm live monitoring map for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, 10 surveyed sites have reported from across the province, nine falling within southern Alberta and one report from the County of Grande Prairie.
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.
Growing season temperatures have been marginally warmer than average while rainfall amounts continue to be well above average. Manitoba continues to have warm temperatures and above normal precipitation. The average 30 day temperature (May 25 – June 23, 2024) was 13.2 °C and was 0.8 °C cooler than the long term average temperature. Warmest temperatures were observed across Manitoba and the southern prairies (Figure 1). Most of the prairies have reported 30 day rainfall amounts were normal to above normal. Rainfall amounts have been greatest in eastern regions and continue to be driest across most of Alberta (Figure 2). Average cumulative rainfall (mm) over the past 30 days was 71 mm and was 138 % of climate normal values (164 % last week). Provincial 30 day values were 54 mm, 73 mm and 97 mm for Alberta, Saskatchewan, and Manitoba, respectively. What a difference a year makes; In 2023 the average temperature for May 27 to June 25 was 17.6 °C (4.4 °C warmer than 2024) and the prairie-wide average cumulative rainfall was 56 mm (104 % of climate normals).
Figure 1. 30 day average temperature (°C) observed across the Canadian prairies for the period of May 25-June 23, 2024.Figure 2. 30 day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 25-June 23, 2024.
Since April 1, the 2024 growing season average temperature has been similar to climate normal values. Warmest average temperatures were observed across a region extending from Winnipeg to Saskatoon and southwest to Lethbridge (Figure 3). Growing season rainfall has been above normal across most of the prairies (Figure 4). Near normal precipitation amounts occurred across western Alberta and western areas of the Peace River region. During May rain amounts were well above average. Over the past few weeks, rainfall amounts have been moving closer to long term normal values. Although rainfall amounts continue to be above average, precipitation amounts (relative to climate normal) are lower in late June than mid-May. For example, as of May 12, rain amounts were 221 % of long term average values. Current rain amounts have been 168 % (191 % last week) of climate normals. Cumulative rainfall has been lowest for a large region than is west of a line that extends from Regina to Grande Prairie (Figure 5).
Figure 3. Growing season average temperature difference from climate normal (°C) observed across the Canadian prairies for the period of April 1 – June 23, 2024.Figure 4. Growing season percent of normal rain (%) observed across the Canadian prairies from April 1 to June 23, 2024.Figure 5. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – June 23, 2024.
Soil moisture values, particularly near the soil surface, can impact the development of soil-borne insect stages (e.g., overwintered or spring stages of eggs, larvae or pupae). Figure 6 presents data to show soil moisture levels (averaged for June 17-23, 2024) in the top five centimeters of soil in western Canada. Driest soil moisture conditions were observed for western regions of Saskatchewan and eastern regions of Alberta. Soil moisture values were greatest for Manitoba and the Parkland region of Saskatchewan. The data is produced from passive microwave satellite data collected by the Soil Moisture and Ocean Salinity (SMOS) satellite and converted to soil moisture using the SMOS soil moisture processor. The data are produced by the European Space Agency. Satellites are used to sense the strength of radiation emitted from the surface of the earth. There is a strong difference in the signals emitted by dry soil and wet soil. This relationship is used to calculate surface soil moisture using a model that incorporates land cover, vegetation content, surface roughness, soil texture and other factors that influence the satellite sensor. The satellite collects data every one to three days over Canada (Satellite Soil Moisture – agriculture.canada.ca).
Figure 6. 7 day average saturated soil moisture (% soil moisture for the surface layer, <5 cm depth) for the period of June 17-23, 2024.
Damaging populations of grasshoppers have been reported in some parts of the prairies this spring. Insecticides have been applied to protect seedlings from grasshopper nymphs.
Scout for grasshoppers to keep informed of their developmental stage and population density.
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. ● 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.
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 erraticwhere 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.
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.
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.
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 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.
There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo). Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.
Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.
There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season, these new adults migrate to overwintering sites beyond the field.
Monitoring:
Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.
Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below for reference; retrieved 2024Jun27).
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.
By this week, a second generation of adult diamondback moth should be active in parts of the prairies.
Pheromone-baited delta traps housing sticky cards are used to monitor diamondback moth across the Canadian prairies. Research has shown that cumulative counts > 25 moths indicate elevated risk. In those areas, it then becomes important to scout and assess larval densities.
Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.
Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre2! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of the diamondback moth.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season started the week of June 10, 2024. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
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 2024.
Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
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.
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.
Track the migration of the Monarch butterflies as they move north by checking the 2024 Monarch Migration Map! A screenshot of Journey North’s “first sightings of adults” map was featured last week. This week, the map of “first sightings of LARVAE” has been placed below (retrieved 27Jun2024) but follow the hyperlink to check the interactive map. Larvae have been spotted in Manitoba so far!
Reminder – Last week, the Prairie Crop Disease Monitoring Network (PCDMN) launched a new website at PrairieCropDisease.com. The PCDMN is a coordinated field crop disease monitoring program for the Prairies, focusing on providing timely information about crop diseases and highlighting effective disease management strategies.
“We are really excited to be launching this new website,” said project lead Dr. Kelly Turkington, Plant Pathologist at Agriculture and Agri-Food Canada, Lacombe Research and Development Centre. “The goal of the network has always been to provide important and timely information to growers and agronomists. By enhancing the functionality of our PCDMN Blog, this new website will greatly improve our communication and engagement, ensuring that stakeholders have access to the latest research and disease management strategies.”
The PCDMN is composed of field crop pathologists who conduct research and actively monitor field crop diseases on the Canadian Prairies. The network includes researchers from Agriculture and Agri-Food Canada, Manitoba Agriculture, Saskatchewan Ministry of Agriculture, Alberta Agriculture & Irrigation, and Prairie-based universities.
“The PCDMN is a valuable resource for farmers, agronomists, and scientists,” says Wayne Thompson, Executive Director of the Western Grains Research Foundation (WGRF). “We are proud to have funded the development of this new website. With this launch, WGRF has successfully developed websites for the three major pest monitoring networks in Western Canada—Insects, Weeds, and Disease. These networks play a crucial role in providing the information needed to anticipate and manage major crop threats.”
The PCDMN also provides weekly updates via email during the growing season. The updates alert subscribers to crop disease risks and management. To view the new site and to sign up for weekly updates please visit PrairieCropDisease.com
Many other organizations have been involved over the years to support this valuable initiative with the 2023-2028 funders including Agriculture and Agri-Food Canada, WGRF, Alberta Canola, Alberta Grains, Alberta Innovates, Manitoba Crop Alliance, Manitoba Pulse and Soybean Growers, Manitoba Canola Growers, Prairie Oat Growers Association, RDAR, Sask Canola, Saskatchewan Ministry of Agriculture, Saskatchewan Pulse Growers, and the Saskatchewan Wheat Development Commission.
Prairie-wide provincial entomologists provide insect pest updates throughout the growing season. Follow the hyperlinks to readily access their information as the growing season progresses:
MANITOBA’SCrop Pest Updates for 2024 are available. Access the online June 27, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include: • Flea beetles – Dr. J. Gavloski reported that, “foliar insecticide applications were reported from all agricultural regions over the past week”. • Cutworms – “Cutworms are still sporadically affecting canola and sunflowers in the Central region. Insecticides were applied to control true armyworms in some forage seed fields in the Interlake. Larvae of true armyworms have also been noticed in cereals in the Central region, but at numbers below threshold.” • Alfalfa weevil – “some spraying” in the Interlake region. • Grasshoppers – “field edge control” in the Central region. • Bertha armyworm pheromone trap monitoring – Access the PDF copy of the June 27 report. • Diamondback moth pheromone trap monitoring – Reports that moths were present “in 75 out of 92 traps” and that, “trap counts have generally been low so far in the Northwest and Southwest regions” but “some moderate to high counts have occurred in the Eastern, Central, and Interlake regions”. The highest cumulative trap count so far is 233 from a trap near Riverton in the Interlake region.” Access the PDF copy of the June 27 report. • True armyworm in MB – “Counts have been low so far in the western regions of Manitoba, with some moderate counts in the Central region” but “higher counts have occurred in some of the traps in the Eastern and Interlake regions”. “The highest cumulative count is 434 from a trap near Riverton in the Interlake region” and “there are areas in the Central, Eastern, and Interlake regions where cereals and forage grasses would be good to prioritize” for armyworm larvae. Access the PDF copy of the June 26 report. • Released a revision of the fact sheet, “Maximizing the value of beneficial insects on the farm“.
SASKATCHEWAN’SCrop Production News is back for the 2024 growing season! Access the online Issue #3 report. Bookmark their insect pest homepage to access important information! A brief summary of the week was provided by Dr. J. Tansey (as of June 27): • Insect pests to watch – “Flea beetles were reported as minor to moderate issue throughout the province with spraying reported in NW and some serious issues reported from a small number of sites in SW”. There was “some minor root maggot damage reported in EC and NE” and “limited moderate wireworm problems in the SW and EC”. “Cutworm pressures were generally low but moderate pressures were reported in the SE”. More recently this week, “barley thrips activity” was reported. • Grasshopper nymphs – “Grasshopper issues were sporadic but moderate pressures were reported in central regions and limited severe pressure in SW.” • Diamondback moth – Preliminary cumulative count data from pheromone traps across the province can now be reviewed online. • Also access the Crops Blog Posts that released a grasshopper activity update, announced registration for the Crop Diagnostic School 2024 but also posts help for scouting fields for wireworms (May 2024), grasshopper identification: pest or not (Apr 2024), a summary of wheat midge populations and management (Mar 2024), and a description of pea leaf weevil populations (Feb 2024).
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, AAF’s Agri-News occasionally includes insect-related information, e.g., soil moisture, wheat midge and other insect pests (June 24, 2024), scout for grasshoppers and other insect pests (June 17, 2024); how to manage stem feeding from flea beetles, keep canola bins malathion-free, scout for grasshoppers and other pests (June 10, 2024); scout for insect pests (June 3, 2024); scout for grasshoppers (May 27, 2024); flea beetle control (May 6, 2024); cereal insect pests, latest on insects in canola, and post-emergence wireworm scouting (May 13, 2024). • Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts from 210 trap locations are all reporting “low risk” category as of June 27, 2024). • Diamondback moth pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts have been recorded from 32 reporting sites and 28 remain in the “no risk” category as of June 27, 2024). Four trap locations have caught > 25 adult diamondback moths; sites fall within the County of Grande Prairie (as of June 8, 2024), County of Warner (as of June 15, 2024), Vulcan County (as of June 15, 2024), and County of Barrhead (as of June 15, 2024). • Cutworm live monitoring map for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, 10 surveyed sites have reported from across the province, nine falling within southern Alberta and one report from the County of Grande Prairie.
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.
Growing season temperatures have been marginally warmer than average while rainfall amounts continue to be above average. This past week (June 10-16, 2024) temperatures were very similar to climate normal values. The average temperature across the prairies was 14.4 °C (Figure 1). Warmest temperatures were observed across most of Manitoba. Average cumulative seven day rainfall was 29.4 mm. Lowest rainfall values were observed across most of Alberta as well as southern regions of Manitoba and Saskatchewan (Figure 2).
Figure 1. Seven day average temperature (°C) observed across the Canadian prairies for the period of June 10-16, 2024.Figure 2. Seven day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 10-16, 2024.
Relative to climate normals, average temperatures have been cooler than normal over the past few weeks. The average 30 day temperature (May 18 – June 16, 2024) was 12 °C and was 1°C cooler than the long term average temperature. The warmest temperatures were continue to be south of an area extending from Winnipeg to Saskatoon and southwest to Lethbridge (Figure 3). Most of the prairies have reported 30 day rainfall amounts were normal to above normal. Average cumulative rainfall (mm) over the past 30 days was 78 mm and is 164% of climate normal values. Rainfall amounts were lowest across Alberta (Figure 4). Provincial 30 day values were 60 mm, 77 mm and 120 mm for Alberta, Saskatchewan and Manitoba.
Figure 3. 30 day average temperature (°C) observed across the Canadian prairies for the period of May 18 – June 16, 2024.Figure 4. 30 day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 18– June 16, 2024.
Since April 1, the 2024 growing season has been 0.5 °C warmer than average. Warmest average temperatures were observed across a region extending from Winnipeg to Saskatoon and southwest to Lethbridge (Figure 5). Growing season rainfall has been above normal across most of the prairies (Figure 6). Only a few, limited, regions have had normal or below normal growing season rainfall (Figure 6 – areas highlighted yellow, orange). Rain amounts have been 191% of climate normals. Cumulative rainfall has been greatest for most of Manitoba and the Parkland region of Saskatchewan (Figure 7).
Figure 5. Growing season average temperature difference from climate normal (°C) observed across the Canadian prairies for the period of April 1 – June 16, 2024.Figure 6. Growing season percent of normal rain (%) observed across the Canadian prairies from April 1 to June 16, 2024.Figure 7. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – June 16, 2024.
Nymphs of economically important grasshopper species have been observed at multiple locations in southern Alberta and southern Saskatchewan since mid-May. This week in Saskatchewan, damaging populations of grasshoppers occurred near Kindersley, Rosetown, and Swift Current. Insecticides have been applied to protect seedlings from grasshopper nymphs.
Scout for grasshoppers to keep informed of their developmental stage and population density.
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. ● 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.
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 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 erraticwhere 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.
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.
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.
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.
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.
The week of May 27, 2024, very mature larvae were retrieved in flixweed in southern Alberta (Barkley, pers. comm. 2024). Thus, a second generation of adult diamondback moth is likely active in southern parts of the prairies.
Pheromone-baited Delta traps housing sticky cards are used to monitor diamondback moth across the Canadian prairies. Research has shown that cumulative counts > 25 moths indicate elevated risk. In those areas, it then becomes important to scout and assess larval densities.
Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.
Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre2! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of diamondback moth.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our Field Guides page.
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.
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.
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 the central, eastern, and Interlake 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.
There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo). Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.
Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.
There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season, these new adults migrate to overwintering sites beyond the field.
Monitoring:
Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.
Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below as an example; retrieved 2022Jul28).
Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season started the week of June 10, 2024.
Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
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 2024.
Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
Track the migration of the Monarch butterflies as they move north by checking the 2024 Monarch Migration Map! A screenshot of Journey North’s “first sightings of adults” map has been placed below as an example (retrieved 18Jun2024) but follow the hyperlink to check the interactive map. They’ve reached Manitoba, Saskatchewan, and (like the Stanley Cup) we look forward to welcoming them back to Alberta!
Two broods, Brood XIX and Brood XIII, live in different regions and began to emerge in the United States in May 2024.
Watch Time’s 2-minute YouTube to find out why 2024 was special for cicadas in North America.
Find out more about periodical cicadas at the University of Connecticut’s website linked to Dr. John R. Cooley‘s MagiCicada Project. Unfortunately, Canadians are not projected to see tremendous cicada emergence this year. However, quoting directly from the University of Connecticut’s website, “2024 is a special year for periodical cicadas: • For the first time since 2015 a 13-year brood will emerge in the same year as a 17-year brood. • For the first time since 1998 adjacent 13-and 17-year broods will emerge in the same year. • For the first time since 1803 Brood XIX and XIII will co-emerge. • You will be able to see all seven named periodical cicada species as adults in the same year, which will not happen again until 2037. You will not see all seven named species emerge in the state of Illinois again until 2041.”
This week, the Prairie Pest Monitoring Network is excited to promote the official launch of the Prairie Crop Disease Monitoring Network’s official website, PrairieCropDisease.com!
The Prairie Crop Disease Monitoring Network (PCDMN) launched a new website today at PrairieCropDisease.com. The PCDMN is a coordinated field crop disease monitoring program for the Prairies, focusing on providing timely information about crop diseases and highlighting effective disease management strategies.
“We are really excited to be launching this new website,” said project lead Dr. Kelly Turkington, Plant Pathologist at Agriculture and Agri-Food Canada, Lacombe Research and Development Centre. “The goal of the network has always been to provide important and timely information to growers and agronomists. By enhancing the functionality of our PCDMN Blog, this new website will greatly improve our communication and engagement, ensuring that stakeholders have access to the latest research and disease management strategies.”
The PCDMN is composed of field crop pathologists who conduct research and actively monitor field crop diseases on the Canadian Prairies. The network includes researchers from Agriculture and Agri-Food Canada, Manitoba Agriculture, Saskatchewan Ministry of Agriculture, Alberta Agriculture & Irrigation, and Prairie-based universities.
“The PCDMN is a valuable resource for farmers, agronomists, and scientists,” says Wayne Thompson, Executive Director of the Western Grains Research Foundation (WGRF). “We are proud to have funded the development of this new website. With this launch, WGRF has successfully developed websites for the three major pest monitoring networks in Western Canada—Insects, Weeds, and Disease. These networks play a crucial role in providing the information needed to anticipate and manage major crop threats.”
The PCDMN also provides weekly updates via email during the growing season. The updates alert subscribers to crop disease risks and management. To view the new site and to sign up for weekly updates please visit PrairieCropDisease.com
Many other organizations have been involved over the years to support this valuable initiative with the 2023-2028 funders including Agriculture and Agri-Food Canada, WGRF, Alberta Canola, Alberta Grains, Alberta Innovates, Manitoba Crop Alliance, Manitoba Pulse and Soybean Growers, Manitoba Canola Growers, Prairie Oat Growers Association, RDAR, Sask Canola, Saskatchewan Ministry of Agriculture, Saskatchewan Pulse Growers, and the Saskatchewan Wheat Development Commission.
Prairie-wide provincial entomologists provide insect pest updates throughout the growing season. Follow the hyperlinks to readily access their information as the growing season progresses:
MANITOBA’SCrop Pest Updates for 2024 are available. Access the online June 20, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include: • Flea beetles in MB – Dr. J. Gavloski reported that, “flea beetles continue to be of concern” with “foliar insecticide applications in all agricultural regions to some degree”. • Cutworms in MB – “Cutworms continue to be found, however, they are becoming less of an issue in some regions as we get into late-June”. • Diamondback moth pheromone trap monitoring in MB – Reports “increased levels of moths in (pheromone) traps in the Central, Eastern and Interlake regions during the weeks of June 2-8 and June 9-15. Moths were present “in 75 out of 92 traps” and that, “trap counts have generally been low so far in the Northwest and Southwest regions” but “some moderate counts have occurred in the Eastern, Central, and Interlake regions”. The highest cumulative trap count so far is 210 from a trap near Stead in the Eastern region.” • True armyworm in MB – “An increase in moths in the true armyworm (pheromone) traps in recent weeks, particularly in the Eastern, Interlake and Central regions. “The highest cumulative count is 411, from a trap near Dencross in the Eastern region” and “there are areas in the Central, Eastern, and Interlake regions where cereals and forage grasses would be good to prioritize” for armyworm larvae.
SASKATCHEWAN’SCrop Production News is back for the 2024 growing season! Access the online Issue #3 report. Bookmark their insect pest homepage to access important information! Highlights pulled from the latest report include: • Insect pests to watch in SK – “Some areas are seeing crop damage from insects including flea beetles, cutworms and grasshoppers”. The summary also advises that, “some insecticides are being sprayed in different areas of the province for these pests. Scout your fields regularly for potential insect damage and make insecticide decisions based on economic thresholds outlined in the 2024 Guide to Crop Protection or by calling the Agriculture Knowledge Centre at 1-866-457-2377”. • Grasshopper nymphs in SK – “Grasshopper activity is high in areas around Swift Current, Aberdeen, Rosetown, Outlook, and Strasbourg.” • Lambda-cyhalothrin products – An important reminder that, “When evaluating insecticide options for fields, keep in mind lambda-cyhalothrin products have application restrictions. Lambda-cyhalothrin products cannot be applied to any crops used for animal feed in any way or that are grazed by livestock. Learn more about lambda-cyhalothrin restrictions in this issue. • Diamondback moth in SK – Preliminary cumulative count data from pheromone traps across the province can now be reviewed online. • Also access the Crops Blog Posts that announced registration for the Crop Diagnostic School 2024 but also posts help for scouting fields for wireworms (May 2024), grasshopper identification: pest or not (Apr 2024), a summary of wheat midge populations and management (Mar 2024), and a description of pea leaf weevil populations (Feb 2024).
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, AAF’s Agri-News occasionally includes insect-related information, e.g., scout for grasshoppers and other insect pests (June 17, 2024); how to manage stem feeding from flea beetles, keep canola bins malathion-free, scout for grasshoppers and other pests (June 10, 2024); scout for insect pests (June 3, 2024), scout for grasshoppers (May 27, 2024), flea beetle control (May 6, 2024); cereal insect pests, latest on insects in canola, and post-emergence wireworm scouting (May 13, 2024). • Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts from 90 trap locations are all reporting “low risk” category as of June 20, 2024). • Diamondback moth pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts have been recorded from 32 reporting sites and 28 remain in the “no risk” category as of June 20, 2024). Four trap locations have caught > 25 adult diamondback moths; sites fall within the County of Grande Prairie (as of June 8, 2024), County of Warner (as of June 15, 2024), Vulcan County (as of June 15, 2024), and County of Barrhead (as of June 15, 2024). • Cutworm live monitoring map for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, 10 surveyed sites have reported from across the province, nine falling within southern Alberta and one report from the County of Grande Prairie.
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.
This past week, cooler temperatures were observed across most of the prairies. Growing season temperatures have been lower than average while rainfall amounts continue to be above average. This past week (June 3-9, 2024) temperatures were 1.2 °C below climate normal values. The average temperature across the prairies was 12.5 °C (Figure 1). Warmest temperatures were observed across a large area that extended west of Winnipeg to Saskatoon and Lethbridge. Seven day cumulative rainfalls were highly variable (Figure 2). Average cumulative seven day rainfall was 16.3 mm. Lowest rainfall values were observed across southern and western regions of the prairies, while the Parkland region had higher rainfall amounts.
Figure 1. Seven day average temperature (°C) observed across the Canadian prairies for the period of June 3-9, 2024.Figure 2. Seven day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 3-9, 2024.
The average 30 day temperature (May 11 – June 9, 2024) was 11.4 °C and was 0.5 °C cooler than the long term average temperature. Warmest temperatures were observed south of an area extending from Winnipeg to Saskatoon and southwest to Lethbridge (Figure 3). Most of the prairies have reported 30 day rainfall amounts were normal to above normal. Average cumulative rainfall (mm) over the past 30 days was 65 mm and was 152% of climate normal values. The Peace River region continues to report lowest rainfall totals (Figure 4). Cumulative rainfall continues to be greatest across most of Manitoba.
Figure 3. 30 day average temperature (°C) observed across the Canadian prairies for the period of May 11 – June 9, 2024.Figure 4. 30 day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 11– June 9, 2024.
Since April 1, the 2024 growing season has been 0.6 °C warmer than average. Warmest average temperatures were observed across the southern prairies (Figure 5). Growing season rainfall has been above normal across most of the prairies. Rain amounts have been 184% of climate normals (Figure 6). Highest cumulative rainfall has been greatest for most of Manitoba and southern Alberta (Figure 7).
Figure 5. Growing season average temperature difference from climate normal (°C) observed across the Canadian prairies for the period of April 1 – June 9, 2024.Figure 6. Growing season percent of normal rain (%) observed across the Canadian prairies from April 1 to June 9, 2024.Figure 7. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – June 9, 2024.
Nymphs of economically important grasshopper species have been observed at multiple locations in southern Alberta and southern Saskatchewan since mid-May. On Jun 6, few grasshopper nymphs were active at sentinel sites between Saskatoon and Rosetosn SK, likely due to cool, wet, and windy conditions.
Scout for grasshoppers to keep informed of their developmental stage and population density.
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. ● 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.
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.
The week of May 27, 2024, very mature larvae were retrieved in flixweed in southern Alberta (Barkley, pers.comm. 2024). Thus, a second generation of adult diamondback moth is likely active in southern parts of the prairies.
Pheromone-baited Delta traps housing sticky cards are used to monitor diamondback moth across the Canadian prairies. Research has shown that cumulative counts > 25 moths indicate elevated risk. In those areas, it then becomes important to scout and assess larval densities.
Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.
Provincial entomologist (Barkley, Tansey, Peru, Gavloski) have kindly provided the following summary for this week: • Alberta – two traps have caught > 25 adult diamondback moths; one trap deployed in the County of Warner (as of June 15, 2024) and one trap deployed in the County of Grande Prairie (as of June 8, 2024). • Saskatchewan – 6 RMs have observed cumulative counts >25 (as of June 6, 2024); traps are located near Regina (RM 129), Macroie (RM 285), Buchanan (RM 304), Laura (RM 315), Delisle (RM 345) and Makwa (RM 428). As of June 6, 2024, the highest cumulative count was 61 moths. • Manitoba – pheromone traps at 20 locations have captured > 25 moths, with cumulative trap catches ranging form 28 to 187. All of the traps with elevated risk are located in the Central, Eastern, South Interlake and North Interlake regions of Manitoba.
Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre2! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of diamondback moth.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network. Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season started the week of June 10, 2024.
Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
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 2024.
Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
