Importance of Photoperiod and Temperature in inducing Diapause in the European Corn Borer, Pyrausta nubilalis (Hbn.)

Abstract

THE European corn borer was first found in Ontario in 1920¹ and, until recently, was primarily a single-generation species, producing one larval brood each summer and overwintering in diapause in the final larval instar. Beginning about 1941, a marked change in the seasonal history of the corn borer occurred. The numbers of larvæ completing development without diapause and giving rise to second-generation larvæ increased until it now constitutes a substantial part of the total borer population². As one approach to an understanding of this divergence in seasonal history, we initiated a study on factors in diapause in the corn borer, including environment.