Toxicity of Malathion and Spinosad to pupal and adult (male and female) stages of the peach fruit fly, Bacterorcera zonata (Saunders) was investigated in laboratory. The adult stage was more susceptible than pupal stage and adult females were more tolerant than males to effect the two insecticides. Malathion and Spinosad were more effective by using residual thin film( LC₅₀=4.28 & 4.51 and 1.14 & 2.50 ppm for males & females, respectively) than feeding technique (LC₅₀ = 6.40 & 6.49 and 2.83 & 4.13 ppm for males & females, respectively).  The results revealed that the resistance ratio of Spinosad (10.0 &10.9 folds for female & male) in field population was higher than Malathion (5.4 & 4.8 folds for female & male) compared with lab insects. The treatment of lab insects with LC₅₀ of Malathion and Spinosad for five generations produced 16 and 4 folds of resistance ratio. Malathion and Spinosad caused a significant depletion of total protein contents in the whole body tissues of treated and resistant insects. Significant increase in activity of Glutathione-S-Transferase and Acetylch-olinesterase enzymes was detected in treated male & female adults.