Abstract: In the field surveys conducted during 1983-1989,eight species of parasitic wasps were found attacking the Asian corn borer(ACB)in cotton fields in the coastal grain and cotton growing areas of Jiangsu Province.A braconid, Macrocentrus linearis was found to be the predominant species.The occurrence of the ACB population peak was delayed for 2-5 days due to high parasitization rate by the braconid parasitoid.Crop damage by ACB was also reduced.