Abstract: Susceptibility to four kinds of insecticides of CoccineUa septempunctata Linnaeus and Propylea japonica (Thunberg) collected from regions where insecticides appli cation levels were different was assayed. Differences of susceptibility of lady birds collected from the same region to different insecticides were remarkable. The order of toxicities was: eyhalothrin ＞ methomyl＞methamidophos＞endosulfan. Toxicity of cyhalothrin to larvae of C. septempunctata was 8560 times higher than that of endosulfanand to adult was 617 times, higher. Differences of susceptibility of C. septempunctata to the same insecticide among populations from different regions were not obvious. But P.Japonica collected from Xiajin county where application level of insecticides was highshowed 30.6 times more resistant to cyhalothrin when compared with the population from Laiwu where the application level of insecticides was low. The selective toxicity of different insecticides to C. Septempunctata and resistant Aphis gossypii differed greatly.The order of selective toxicities was: endosulfan＞methomyl＞methamidophos＞cyhalothrin. The selective toxicity index of endosulfan was 4. 9 where as the selective toxicity index of cyhalothrin was only 7. 3 × 10^-6. Endosulfan is recommended to control the resistant A. Gossypii.

Key words: Coccinella septempunctata Linnaeus, Propylea japonica (Thunberg), Aphis gossypii Glover, insecticides, selective toxicity