No. 15 Article 3/July 3, 2008

Begin Monitoring for Western Bean Cutworm Adults

Several University of Illinois Extension educators have erected western bean cutworm pheromone traps to begin monitoring for the adults. As you know, the western bean cutworm was first found in Illinois in 2004, and we (and other extension entomologists in the Midwest) have been monitoring for the moths ever since. Results from the vast monitoring effort (which includes agricultural seed and chemical company representatives) are reported on Iowa State University's "Western Bean Cutworm Monitoring Network". The moths typically are monitored from mid-June to mid-August.

Pheromone trap used to monitor for western bean cutworm adults (photo courtesy of Marlin Rice, Iowa State University).

After they emerge (just beginning, based on a couple of reports of captures), western bean cutworm females mate, and the females lay their eggs on the upper surfaces of corn leaves, usually near the tops of plants. After hatching, the larvae move either to the whorls (which they might encounter this year) to feed on the tassels or to the ears (if present). Feeding by western bean cutworm larvae in corn ears can cause economic damage; we'll discuss this in more detail in a future issue of the Bulletin.

The western bean cutworm is not thoroughly established as a widespread threat to corn in Illinois. However, it has been found in many counties, particularly noticeably in the northwestern and north-central counties, and as of 2007 it had been found as far east as Michigan and Ohio. We'll keep tabs on the moth flights and let you know whether larvae are found in either whorls or ears.--Kevin Steffey

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