2023 Week 1 (Released May 10, 2023)

Welcome to the first Weekly Update for the 2023 growing Season!

As planting and insect scouting are just getting started, this Weekly Update focuses on two important insects to watch out for early in the season, grasshoppers and alfalfa weevil. The first Insect of the Week (which unfortunately did not get emailed out earlier this week) is a timely reminder to watch out for flea beetles.

The prairie-wide maps summarizing the results from the 2022 growing season are online and available for review, as are the historical insect pest distribution maps. These prairie-wide geospatial maps offer insight into potential risk and help growers prioritize their scouting lists.

Remember, insect Monitoring Protocols containing helpful insect pest biology, how and when to target in-field scouting, and even thresholds to help support in-field management decisions are all available for review or download.

Wishing everyone good weather and let the insect scouting begin!

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Questions or problems accessing the contents of this Weekly Update?  Please contact Dr. Meghan Vankosky (meghan.vankosky@agr.gc.ca) to get connected to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

Weather Synopsis

Since April 1, the 2023 growing season has been cooler than average and marginally wetter than normal. It has been coolest across Manitoba and central Saskatchewan (Fig. 1). This past week (May 1-7, 2023), the average temperature across the prairies was 5°C warmer than normal (Fig. 2). Temperatures were warmest across Alberta and western Saskatchewan and cooler over eastern Saskatchewan and Manitoba.

Figure 1. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to May 7, 2023.

Figure 2. Seven-day average temperature (°C) observed across the Canadian prairies for the period of May 1-7, 2023.

Growing season rainfall has been near normal across most of the prairies so far in 2023, with the greatest accumulations reported across southern Manitoba and Saskatchewan (Fig. 3). Between May 1 and May 7, 2023, the 7-day cumulative rainfall was marginal across most of the prairies (Fig. 4).

Figure 3. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to May 7, 2023.

Figure 4. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 1-7, 2023.

Predicted Grasshopper Development

The grasshopper model predicts development of the migratory grasshopper (Melanoplus sanguinipes) and closely related species using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Review lifecycle and damage information for this pest. Review the historical grasshopper maps based on late-summer adult in-field counts performed across the prairies. Results from the 2022 late-summer adult grasshopper survey are shown in Fig. 1.

Figure 1. Adult grasshopper densities in late summer of 2022.

Model simulations were used to estimate development of grasshopper eggs as of May 7, 2023. Compared with average spring temperatures, well above normal temperatures in Alberta and western Saskatchewan thus far this spring are predicted to result in rapid grasshopper egg development (Fig. 2). As a result, grasshopper egg development in 2023 is expected to be advanced as compared to egg development in average growing seasons (Fig. 3). Cool conditions in Manitoba have resulted in slower rates of egg development. Areas with the highest adult grasshopper densities in summer 2022 (Fig. 1) overlap with regions where egg development is predicted to be most advanced so far in spring 2023 (Fig. 2). Based on the 2022 survey, high densities were reported across a large region that extended south of the Yellowhead Highway corridor to the Canada-USA border (Fig. 1).

Prairie farmers should be prepared to scout for grasshoppers in spring and early summer this year, especially if conditions remain warmer and drier than normal.

Figure 2. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian Prairies as of May 7, 2023.

Figure 3. Long-term average predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 7, 2023, based on climate normals data.

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



The 2023 Insect of the Week season kicks off by featuring these small yet economically important beetles. Flea beetles have already been spotted across the prairies. Growers need to be wary of flea beetles even in the initial 7 days following seeding of their host crops, including canola. The best defense is in-field scouting from germination until the first true leaves unfurl and enlarge in size beyond the cotyledon leaf area. The adults create shot-hole damage visible on the topsides of the highly vulnerable cotyledons of canola but careful scouting also involves checking for feeding damage on the undersides of cotyledons and tiny canola stems where they also can feed.

Crucifer Beetle on Canola Leaf — photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org

Several species of flea beetles are present across the Canadian prairies and not all are considered pests. Historically, crucifer (Phyllotreta crucifer), striped (Phyllotreta striolata), and hops (Psylliodes punctulata) flea beetle species have caused damage in canola. Over the past decade, the bluish-black crucifer and black-with-yellow-lined striped flea beetles have proven to be consistent economic pests in canola grown across the Canadian prairies.

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

Striped and crucifer flea beetles feed on canola, mustard and related cruciferous plants and weeds. Canola is highly susceptible to feeding damage at the cotyledon stage – damage appears as ‘shot-holes’ in cotyledon leaves. Flea beetles also feed on stems and very young seedlings may wilt or break off under windy or damp conditions. New generation adults feed on maturing pods late in the summer. Remember, the Action Threshold for flea beetles on canola is when 25% of cotyledon leaf area is consumed.

*Information here was compiled from past PPMN Insect of the Week feature articles about flea beetles.

Key links for more information and to aid in field scouting include: