The concentration–mortality response of Musca domestica L. (Diptera: Muscidae) to nine insecticides, and the impacts of these insecticides on selected biological and biochemical parameters of the insect, were determined in laboratory assays. Adults displayed a concentration-dependent response for each insecticide. Median lethal concentration (LC₅₀) values in baits were: acetamiprid (0.39 μg/ml), bifenthrin (0.22 μg/ml), chlorpyriphos (0.21 μg/ml), deltamethrin (0.41 μg/ml), emamectin benzoate (0.001 μg/ml), fipronil (0.002 μg/ml), imidacloprid (0.27 μg/ml), profenophos (0.63 μg/ml), and lufenuron (0.001 μg/ml). Based on 95% confidence intervals, fipronil proved to be the most lethal of the insecticides tested. LC₁₀, LC₃₀, and LC₅₀ values of each of the insecticides were used to assess impacts on M. domestica longevity, fecundity, percentage eclosion, larval duration, percentage pupation, pupal weight, pupal duration, adult emergence, and sex ratio. In general, development parameters, with the exception of larval duration, were significantly (P > 0.05) altered in a concentration-dependent manner for each insecticide. Furthermore, enzymatic activity of total glutathione S-transferases, total esterases, acetylcholinesterase, and acid and alkaline phosphates was elevated at the LC₁₀, LC₃₀, and LC₅₀ levels of the nine insecticides, which may contribute to development of resistance to these insecticides.