While sitting in a restaurant in Tuscola (Douglas County) on Saturday, I observed several European corn borer moths on the window and in bushes beside the window. (OK, so maybe I need to get a life.) Kevin Black with Cargill also reported captures of relatively small numbers of adults in his light trap in McLean County during the week of July 24. Although European corn borers have not raised many eyebrows this summer, the presence of moths indicates that egg laying is ongoing. It is possible that numbers of surviving larvae in some cornfields could be large enough to get our attention. This is especially true for late-planted corn; the females laying eggs for the second generation prefer to lay eggs in pollinating corn with fresh silks. Even though the price of corn is low, heavy infestations of European corn borers might be worth controlling in fields with high-yield potential.
The southwestern corn borer is a distinctly more critical concern in southern Illinois. Ron Hines, senior research agronomist at the Dixon Springs Ag Center, has been monitoring flights of several moths, including the southwestern corn borer, all summer. The numbers of southwestern corn borer adults he caught in two different types of traps were extraordinarily large in mid- to late July, so the potential for heavy infestations is significant. In issue no. 16 (July 14, 2000) of the Bulletin, I discussed the biology of the southwestern corn borer and offered scouting techniques, static economic thresholds, and suggested insecticides. Keep this information handy while you are looking for southwestern corn borer eggs and larvae. Again, there's no need to lose a lot of yield to this pest if you stay on top of the situation.--Kevin Steffey