Populations of Chrysoperla carnea (Stephens) were resistant to a wide range of insecticides, including most of the commonly used groups (pyrethroids, organophosphorous insecticides, carbamates) used in orchards. Resistance was partially because of enhanced metabolism of pesticides by resistant C. carnea larvae. Metabolism was by oxidative and esteratic routes; the relative importance of the two systems depended upon the pesticide. In laboratory cultures, resistance to organophosphorous insecticides declined approximately 10 times (3 times for pyrethroids) over 3 yr, suggesting that careful quality controls are required for mass-rearing programs. Provided that resistance can be stabilized at high levels in the laboratory colony, the wide range of resistance shown here makes C. carnea a prime candidate for mass releases of pesticide-resistant beneficial organisms for use in IPM programs.