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A Reminder About Several Insects in Corn Right Now

July 14, 2000
A note from John Irle with Illini FS reminded me to offer a few comments about several different insects that might be found in cornfields right now. Although we typically focus on one insect per article in the Bulletin, we are fully aware that those of you who scout must look for a whole gang of insects that might present problems. In addition to the corn rootworms, grape colaspis, southwestern corn borers, and European corn borers discussed in previous articles, you may encounter any number of other insect pests that we have discussed at various times this season. John indicated that in virtually all fields he has scouted in Champaign and Douglas counties, he can find infestations (although none of them economic) of corn rootworm adults, Japanese beetles, grasshoppers, corn leaf aphids, and woollybear caterpillars. Corn rootworm adults, Japanese beetles, and woollybear caterpillars all clip silks, and grasshoppers and corn leaf aphids can also interfere with pollination and yield potential.

The saga of the Japanese beetle during the past couple of years has spread to many relatively new places in Illinois, and people are wondering if this pest is here to stay. Well, it certainly will be around for years to come; whether densities of Japanese beetles reach economic levels every year is another story. It's likely that mild winters, early planting, and possibly other factors have contributed to their success during 1999 and 2000. One more reminder: begin to watch in earnest for Japanese beetles in soybeans.

Although we have not mentioned woolybear caterpillars this year, their presence always bears watching. It is not common for us to experience economic infestations of these pests, especially in corn. Although they clip silks, they usually move from ear to ear, so the silks continue to grow after being clipped off. However, their presence now suggests that we need to watch for them showing up in soybeans soon. Fortunately, wet weather promotes the spread of a fungal disease organism that regulates populations of woollybear caterpillars.

Keep the reports coming, regardless of what you find (or don't find). Our knowing that not much is happening in your area is just as important as our receiving reports of significant problems.--Kevin Steffey

Author: Kevin Steffey

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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