Laboratory-reared males, females and third instar nymphs of the insidious flower bug, Orius insidiosus, were exposed to residues of nine insecticides applied to cotton plants in the field, in potted plants in the greenhouse and glass petri dishes in the laboratory. Insects were exposed for 24-hours and then removed to determine mortality. Insecticides tested were spinosad, indoxacarb, imidacloprid, tebufenozide, methoxyfenozide, abamectin, emamectin benzoate, fipronil and λ-cyhalothrin. Differences were observed in mortality as measured by different methods. Spinosad, imidacloprid and indoxacarb induced significantly higher mortality with treated petri dishes than on treated cotton plants in the field or greenhouse. It is apparent that multiple testing methods should be used in evaluating the effects of pesticides on beneficial arthropods.