Start Watching for the Next Generation of European Corn Borers

July 9, 1999
Although we made it through this part of the growing season without any problems from first-generation European corn borers, we will have to be vigilant for the second generation. As I indicated in last week's Bulletin (issue no. 15, July 2, 1999), we occasionally experience heavy infestations of second-generation borers after being lulled to sleep by wimpy first-generation numbers. Ron Hines, research specialist at the Dixon Springs Ag Center, has reported a slight upswing in numbers of European corn borer adults captured in traps, suggesting that the flight of moths that will lay eggs for the second generation has begun.

Some intriguing information has come from Carol Parrish at the Monsanto Agronomy Center in Monmouth. In their traps, the numbers of European corn borer adults increased dramatically on June 23 and 25, much too early for moths that will lay eggs for the second generation in that part of the state. We have heard of almost continuous flights of European corn borer adults throughout the summer in certain areas of Illinois for a few years. We have speculated, with some supporting evidence, that we may have the univoltine (one generation) European corn borer (same species, different ecotype) mixed in with our typical bivoltine (two generations) corn borer. The peak flight of the univoltine corn borer usually occurs between the peak flights of our first- and second-generation borers. As we have stated in the past, such an occurrence will make managing European corn borer in non-Bt corn a bit more difficult.

European corn borer adults.

During the next few weeks, keep your eyes peeled for the emergence of European corn borer adults. You should notice them as you walk through weedy and grassy areas surrounding cornfields, and maybe as you drive through the country at night. Report what you find so we can alert others. Your cooperation is greatly appreciated.--Kevin Steffey

Author: Kevin Steffey