Biochemical studies of both early and late 3rd larval instar of Musca domestica treated with water extract of four plants: C. procera, H. muticus, D. stramonium and Z. album at a dose of 100 μg | larva showed that; the mean total carbohydrate content was significantly increased after 24 hours from treatment. The most effective one was H. muticus extract. Also the mean total lipid content was significantly increased and the most effective one was C. procera extract. A significant decrease in the mean total protein content had occurred and the most effective extract was C.procera extract.