No. 20 Article 3/August 10, 2007

A Note About Western Bean Cutworms

In general, a review of the data on the Iowa State University "Western Bean Cutworm Monitoring Network" Web site suggests that significantly fewer western bean cutworm moths were captured in pheromone traps in Illinois in 2007 than in 2006. One has to wonder whether the emphasis on accurate identification of moths captured in pheromone traps this year played any role in these lower numbers in 2007 (in other words, potential misidentifications last year) or whether environmental conditions in 2007 have been less suitable for the species.

We have not received much followup regarding reports of western bean cutworm larvae in corn fields near pheromone trapping sites, but we encourage people to look for the larvae in corn fields now. Jim Donnelly, crops specialist with Ag View FS in Walnut, found western bean cutworm larvae feeding in a corn field in Bureau County in late July. Some of the larvae were as long as 3/4 inch. Although he did not know the density of larvae, he indicated that they "were quite easy to find."

It is not easy to confirm that injury to corn ears was caused by western bean cutworms after the larvae have finished feeding and dropped to the ground to pupate. So look now if you want to know whether this is an insect to consider when developing insect management plans for 2008.--Kevin Steffey

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