Western Corn Rootworms Common in Some Soybean Fields in Northern Illinois Counties

August 27, 1999
Last week during a field day at the Northern Illinois Agronomy Research Center, DeKalb County, I observed impressive numbers of western corn rootworm adults in a soybean field located on the farm. Eli Levine, a researcher with the Illinois Natural History Survey, has vial traps throughout the soybean field I examined. These vial traps are passive; that is, they do not attract western corn rootworm adults. Instead, beetles climb through small openings in the vials and feed on an insecticidal bait (cucurbitacins and carbaryl) placed on a narrow strip of paper. A quick examination of the vial traps revealed an abundance of western corn rootworm adults. Although we found western corn rootworm adults in a few soybean fields in DeKalb County last year, the densities were quite low.

Jim Morrison, Crop Systems Educator, Rockford Extension Center, reported that producers in Lee County who are using Pherocon AM sticky traps in their soybean fields have found western corn rootworm adults with little difficulty this year. The bottom line: this "new" western corn rootworm that lays eggs in soybean fields has spread to northern counties somewhat faster than previously expected. I hope that you took the time this season to at least look in your soybean fields for western corn rootworm adults. If not, now is the time to take a close look. These beetles can be found commonly in many cornfields and soybean fields through at least the first 10 days of September. The advice to monitor your soybean fields includes those producers in so-called "nonproblem" areas of northern and western Illinois. Please pass along any of your observations of western corn rootworm beetles in soybean fields, particularly in those areas outside of east-central Illinois.--Mike Gray

Author: Mike Gray