Field strains of copea Aphis craccivora selected (in October 2008) from different Governorates (Behira, Gharbia, Sharkia and Faiyoum) were treated by different groups of insecticides, to evaluate their efficacy against this pest and to study some biochemical characters of these strains. The novel compound thiamethoxam (neonicotinoid) was the most effective one followed by diafenthiuron (thiourea compounds), carbosulfan   (carbamate) and esfenvalerate (pyrethroid) in the all tested Governments except Sharkia, diafenthiuron was the least effective one (LC₅₀ 232.80 ppm), while carbosulfan was the least effective one at   Gharbia Governorate (LC₅₀ 109.7ppm.)  Differences in protein content, protein patterns, esterase activity, alkaline and acidic phosphatase were detected and differed from population to another.