Abstract: Influence of three insecticides on weight and development duration of
the spider Hylyphantes graminicola (Sundevall) was investigated by two feeding methods in laboratory. Results showed that weight of the female spider decreased more significantly when they were fed on dimethoate and fenvalerate using touchingpoison method than that of the control. And, the weight of the male decreased more significantly when they were fed on deltamethrin by feedingpoison method than that of the control. The above three insecticides did not significantly influence weight of the male spider when applied by touchingpoison method. The 3rd instar did not, while the 4th and 5th instars did, differ in durations from those of the control when fed on three insecticides. Generally, the insecticides prolonged and retarded development of H. graminicola, and resulted in a decrease in weight.