Oxythioquinox was the only 1 of 5 chemicals recommended for control of Trialeurodes vaporariorum (Westwood) which was not toxic to its chalcid parasite Encarsia Formosa Gahan. Oxythioquinox at 0.01 % killed 50% of whitefly adults, about 80% of the eggs, and also controlled cucumber powdery mildew. An integrated control program with a parasite release followed by 3 oxythioquinox sprays at 2-week intervals provided whitefly control, and the parasite numbers increased rapidly.