Abstract:Through analysis of the investigation data of the Asian corn borer,Ostrinia furnacalis (Guenée) (ACB), overwintering generation in the piles of maize stalks in Gongzhuling City, Jilin Province, a conclusion is reached on the appearing stage, initial peak stage, peak stage, ending peak stage and disappearing stage during the pupation of the overwintering generation. Through analysis to the systematic investigation data in field, it is determined that the appearing stage, initial peak stage, peak stage, ending peak stage and disappearing stage of the first and second generation eggs. The percentage of hatching is more than 90%, and the parasitism and predatoriness percentage of the eggs is relatively low in the first generation . The pupation rate is from 89% to 94% in the first generation. The parasitization rate of egg masses by Trichogramma spp. is 70% in the second generation ACB. There are less eggs were predated and dropped in the period. The percentage of mature larvae is 92.7% and no pupae are observed in the second generation ACB when dissecting the corn stalks in the middle of September. The occurrence of the ACB have changed from one and a half generations into two generations in the middle region of Jilin Province.