The cotton aphid, Aphis gossypii Glover (Hemiptera-Aphididae), is one of the most important sap sucking pests in many cotton-growing areas world-wide. In this study, the efficacies of eight insecticides organophosphate (Dimethoate, Malathion and Pirimiphos-methyl), carbamate (Pirmicarb and Methomyl), pyrethroid  (Etofenprox,  Lambda-cyhalothrin and Cypermethern)  were determined against four strains of A. gossypii (Glover) collected from three Governorates in 2013 and four Governorates in 2014  (Sharkia,  Gharbia, Behera and Fayum). Collected strains were bioassay and compared with a reference Laboratory strain. Results indicated that the carbamate Pirmicarb and Methomyl were the most effective insecticides and recorded the least resistance levels and the highest toxic action when compared with the other tested organophosphates insecticides. A similar results were obtained in the case of the organophosphate (Dimethoate, Malathion and Pirimiphos-methyl), while pyrethroid insecticides   were more resistance levels and least toxic action, also analyzed protein of all field strains tested by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and electrophoretic patterns of esterase isozyme during the adult stage were determined.