Buprofezin and imidacloprid are selective insecticides against Homoptera insects. This paper in-vestigated stimulating effect of the two insecticides on the number of laid eggs by yellow rice borer, Tryporyzaincertulas (Walker) of three generations in 2001 -2002. The results showed that the reproductive rate of emer-gence months during the larvae feeding on the rice plants of Xiushui63 treated with the two insecticides was sig-nificantly higher than that of control, indicating that the numbers of laid eggs by the borer was stimulated fol-lowing buprofezin and imidacloprid applications. However, there was no such effect for the larvae feeding onrice variety Zhendao2 which showed moderate resistance to the insect. In addition, the incidence of stimulatingegg laid for the first instar treated with the two insecticides was greater than that for the third instar. Bio-chemical tests showed that oxalic acid concentration declined, and photosynthetic rate of rice leaves followingthe two insecticide applications declined significantly compared to control, whereas reducing sugar concentra-tion increased significantly for all other treatments of two varieties except Xiushui63 treated with buprofezin.The level of glutathione-S-transferase varied with rice variety and insecticide.