Compared to last week, near normal temperatures have resulted in expected development of grasshopper eggs. This week, as of May 15, 2019, predicted development was 63% and is similar to long term average values (Fig. 1).
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| Figure 1. Predicted grasshopper (Melanoplus sanguinipes) embryological development acrossthe Canadian prairies as of May 15, 2019. |
Model runs for Lethbridge (Fig. 2) and Saskatoon (Fig. 3) were projected to June 15, 2019. Results indicated that eggs should begin to hatch next week. Model predictions, based on long term normal weather data predict that initial hatch near Saskatoon should occur on May 25th.
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Figure 2. Predicted status of Melanoplus sanguipes populations near Lethbridge AB as of May 15, 2019. |
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Figure 3. Predicted status of Melanoplus sanguipes populations near Saskatoon SK as of May 15, 2019. |
Reminder - The Prairie Pest Monitoring Network's 2019 Grasshopper Forecast Map was released in March. Review all the current risk and forecast maps by linking here. While spring temperatures, soil moisture conditions, and precipitation can all have an impact on overwintered grasshopper eggs, areas highlighted orange or red in the 2019 forecast map should be vigilant this spring by performing in-field scouting to assess nymph densities.
Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba Agriculture, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network. Also refer to the grasshopper pages within the new "Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide" as an English-enhanced or French-enhanced version.
