Abstract: Qstrinia furnacalis has the following parastoid, namely Macrocentrus linearis 71.6% Lydella grisescens 22.4%, with a few others based on a series of field investigation in Yncheng, Jiangsu from 1977 to 1993. The rate of first generation larvae being parasitized ranged from 16.5 to 75.8%. Infestation of first generation as well as the generation followed was often dependent on the rate of parasitization, which was found to be significantly or related to the amo unt of the first generation egg mass, average precipitation in May and average temperature in June. The rate of first generation larvae being parasitized could be predicted by a regression equation before the end of June.