Dichlorvos (DDVP; 2,2-dichlorovinyl dimethyl phosphate) is an organophosphate insecticide widely used in the control of pests. This study aims to determine the changes caused by DDVP in the antioxidant enzyme activity, lipid peroxidation level, and ion content of a model organism, Galleria mellonella L. (Lepidoptera: Pyralidae). Larvae of G. mellonella were fed sublethal concentrations of DDVP (2, 4, 6, and 8 mu g/100 g feed). Exposure to DDVP resulted in induction of superoxide dismutase and catalase activities, and lipid peroxidation in larvae. Potassium and sodium ion levels were significantly altered by DDVP exposure. These results suggest that DDVP causes oxidative stress and lipid peroxidation and alters the antioxidant enzyme activities and ion balance in G. mellonella larvae. Additionally, these results indicate that G. mellonella is a useful model for testing the effects of insecticides.