【Abstract】 Sensitivity of Aphis gossypii, A. spiraeccla and Macrosiphum avenae in various places of Hebei province to imidacloprid were determined. The results showed that no significant differences were found in the sensitivity of Aphis gossypii and Macrosiphum avenae to the insecticide among the various places, but the sensitivity of A. spiraeccla in Xinji Changli and Qingyuan were 2.02~4.13 times lower than that in Yixian. It suggests a possiblility of imidacloprid resistance of A. spiraeccla in some places. A strain of Aphis gossypii was selected in laboratory with imidacloprid for 7 months, and its sensitivity was 4.5 times reduced .更多还原