To better understand the side-effects of pesticides on nontarget insects, exposure and mortality assessment tests were performed with the parasitic wasp, Aphidius colemani. Quantities of chlorothalonil (TPN) and spinosad in individual wasps were determined using commercially available ELISA kits. TPN showed no side-effect on contact with dry film or oral administration. The lethal dosage of spinosad on plant leaves was estimated at ca. 0.2 mg/cm2 for individual wasps, and was supported by the results of residual activity tests. Furthermore, a minimum of around 0.1 ng of spinosad was observed in dead individuals exposed to plant leaves treated with a lethal dosage of the pesticide.