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A Few Insect "Thumbnail" Reports

July 12, 2002
· Mark Fromme, with Lincoln Land FS, recently observed a fairly significant number of corn leaf aphids in late-whorl stage corn in his area. He estimated that 20 to 25% of the plants were infested. In areas of Illinois where moisture is lacking, people will need to be vigilant for corn leaf aphids, especially during pollination. Large colonies of corn leaf aphids can interfere with pollination. In addition, the aphids' feeding habits (sucking water and nutrients from the plants) make matters worse during hot, dry weather. As you scout for corn leaf aphids, keep an eye open for lady beetles, which are very effective predators.

· John Shaw, research scientist with the Illinois Natural History Survey, has been capturing large numbers of grape colaspis adults in emergence cages during the past couple of weeks. Although the cages are designed to capture corn rootworm adults, thus far he has captured far more grape colaspis adults. You will begin finding these insects in both corn and soybeans in July, so watch for them. They resemble corn rootworm adults in size and shape, although they are a bit more "domed" in appearance. The grape colaspis adult is oval, tan, and about 1/6 inch long with rows of tiny punctures on its wing covers, making them appear ridged.

Grape colaspis adult. (Photo courtesy of Andy Knepp.)

· Grasshoppers continue to create concern in many areas of Illinois, especially in southern and western counties. We have received some reports that they have begun moving into crop fields. If the hot, dry weather continues, their movement into crop fields will accelerate. Keep scouting.

· Potato leafhoppers started slowly this year, but they're making up for lost time. Densities in many alfalfa fields are well above established economic thresholds. Potato leafhoppers also are showing up in and causing injury to soybeans. Although their injury to soybeans usually is not economic, current growing conditions may warrant a closer look at leafhoppers in soybeans.

· The flight of southwestern corn borer moths that will lay eggs for the second generation has begun in southern Illinois. Ron Hines, senior research specialist at the University of Illinois Dixon Springs Agricultural Center, has begun to capture large numbers of moths in his traps (refer to "The Hines Report" located on the Web at People in southern counties should begin scouting cornfields for egg masses of southwestern corn borers. We will provide control recommendations in the next issue of the Bulletin.

· The hot, dry weather (I'm sounding like a broken record) is encouraging buildup of twospotted spider mites in the margins of soybean fields in some areas of Illinois. Remain watchful; their numbers can increase in a hurry under the current environmental conditions.

Thanks for all of your input and feedback thus far this year. We hope the sharing of reports from around the state is useful.--Kevin Steffey

Author: Kevin Steffey

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

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