Western bean cutworm traps catches are starting to increase but are still low compared to previous years with more weeks of moth flight (and egg laying) to come. Those finding eggs in early tassel stage need to wait before spraying since eggs are still going to be laid for another few weeks. It is better to time applications when the corn is in full silk but not already in brown silk. This will target as many of the larvae that come from the next few weeks of increased egg laying.
You can see the latest GLMPMN map for WBC trap catches below and at this link. https://ontarioca11.maps.arcgis.com/apps/MapSeries/index.html?appid=4f19db5a8c3547f397825be8a07e80fa
Just click on the “WBC” tab at the top of the GLMPMN site to see the map and zoom into your region or click on the “Dashboard” tab and select western bean cutworm as the pest to see the graphs for the trap data. You can then zoom in and out of the map and see the graphs change to analyze traps in the area where the map is zoomed into.
Comparing average trap catches this week with this same week in past years, we have some weeks of moth flight to go still. 2021 is in red and very low compared to past years. Peak flight since 2018 has been during the last week of July. So there is still more egg laying to come.
Scout the most advanced corn fields first. Look at all leaves from the ear up to the tassel. Take note of whether the eggs are fresh (white) or close to hatching (purple). Scout every 5 days so you can see how these egg masses are progressing. Also inspect the tassel for any tiny larvae that are feeding there. If after 3 scouting trips, 5% of the plants in the field have had eggs, threshold has been reached.
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