Biological Observations on the European Corn Borer in Southeastern Missouri1

The European corn borer, Ostrinia nubilalis (Hübner), has the capability of completing 3 generations per season in the Sikeston, Missouri, area. Fewer than 12% of the larvae of the first generation entered diapause and more than 50% of the larvae of the second generation entered diapause. At least 90% of the mature larvae of the third generation entered diapause and there was no evidence of a fourth generation. Larvae of the fourth generation would not have been able to complete development before the first killing frost. The European corn borer population in the Sikeston area completes 1, 2, and 3 generations per year and we would therefore call it heterovoltine. European corn borer females oviposited more in relation to the growth stage of corn than to variety or height. The length of maturity of the variety bears a direct relationship to the level of infestation by European corn borer. There were no significant differences between US. 13 and US. 13 Dwarf in levels of infestation of European corn borer as determined by oviposition, fall larval infestations, or total cavities. Yield was significantly different. There was a significant correlation of total cavities with total larvae under most of the conditions in the investigation. It was not possible to correlate levels of infestation with yield reduction on a single-stalk basis.