University of Illinois

No. 14/June 27, 1997

A Potpourri of Findings and Possibilities

As you folks focus most of your attention on European corn borers in corn, many other insects and their relatives have caused headaches here and there in fields of corn, soybeans, and alfalfa. On June 19, Mike Porter with Zeneca observed a field of corn in Stephenson County that was fairly heavily infested with slugs. Although the report seemed surprising due to the dry, warm conditions, Mike indicated that the field had been planted to barley last year. The residue probably provided a suitable habitat for the slugs. He also reported continuing problems with stalk borers in northwestern Illinois.

Jim Stine (don't yell at me, Jim, if I've spelled your name incorrectly) with AgriPride FS in Benedy observed chinch bugs feeding at the bases of corn plants in a field in Washington County a couple of weeks ago. I also received a report from someone about a similar problem in Fayette County at about the same time. Chinch bugs usually show up in cornfields adjacent to wheat fields that are maturing. The chinch bugs leave the wheat and move into corn to obtain their nutritional requirements. Masses of nymphs and adults usually can be found in large congregations at the bases of cornstalks as they suck sap from the plants.

Kyle Cecil with the Extension Service in Knox County has discovered blister beetles feeding in alfalfa. Although their occurrence in large numbers in localized spots in the fields often causes alarm, their feeding on alfalfa rarely is economic. More importantly, blister beetles in alfalfa hay can cause some serious health hazards to horses, which are particularly sensitive to the chemical cantharadin, the substance in blister beetles that causes the blisters that gives them their name. Fortunately, cows are not affected very often because they usually will not eat hay in which crushed blister beetles are present.

As the summer progresses, we await the onset of insects like corn rootworms and corn leaf aphids in corn. In soybeans, people should be watching for any number of defoliators that consume leaf tissue during July, including bean leaf beetles, green cloverworms, and grasshoppers. In areas where the weather remains hot and dry, it's not out of the question that spider mites could begin to make their presence known. In addition, current weather conditions are conducive to potato leafhoppers, both in soybeans and in alfalfa. Numbers of potato leafhoppers in alfalfa have been relatively impressive already. As the life cycle progresses from females laying eggs to nymphs developing into adults, their numbers could increase dramatically.

These are just a few thumbnail sketches of problems that could be encountered right now or some that might be discovered within the next couple of weeks. Stay alert, and stay in touch.

Kevin Steffey, Extension Entomology, (217)333-6652