First-generation European corn borer larvae have tunneled into stalks in most areas of Illinois, and moths that will lay eggs for the second generation will be emerging soon. In fact, if you want to keep track of development of the second generation, you can consult Table 2. To use the table, you will have to have some record of the initial capture of moths this spring, and you'll have to keep track of degree-day accumulations above a base temperature of 50 deg F. In the future, we intend to provide this information to you in an interactive fashion on the Web.|
For the most part, infestations of first-generation European corn borers in Illinois this year were not economic. However, whorl-feeding injury was significant in some fields in northeastern Illinois. Randy Kline in Kane County scouted one field that had 80% whorl feeding. Kevin Black, with Growmark, observed fields in northeastern Illinois with 100% whorl feeding. Among all crop reporting districts in Illinois, the Northeast Crop Reporting District had the highest overwintering population of corn borer larvae during the 2001-2002 winter.
If European corn borers survived through the first generation, we will have to watch carefully during development of the second generation. Our records indicate that a large second generation may develop during the summer after seemingly small populations of first-generation borers occurred during the spring. The survival of European corn borers will depend on weather and the effects of natural enemies and disease organisms. With other insect concerns right now, let's hope Mother Nature helps us out a bit here.--Kevin Steffey