BACKGROUND: Chlorantraniliprole is a novel anthranilic diamide insecticide, efficacious for control of lepidopteran insect pests, as well as some species in the orders Coleoptera, Diptera and Hemiptera. In this study, the speed of action of chlorantraniliprole was compared with that of seven commercial insecticides by means of ingestion bioassays against larvae of Plutella xylostella L., Trichoplusia ni (Hübner), Spodoptera exigua (Hübner) and Helicoverpa zea (Boddie). RESULTS: Based on feeding cessation and reduction in feeding damage, chlorantraniliprole is among the fastest-acting insecticides available for control of lepidopteran pests, comparable in speed of action with methomyl, lambda-cyhalothrin and esfenvalerate, and faster than emamectin benzoate, indoxacarb, methoxyfenozide and metaflumizone. CONCLUSION: The speed of action of chlorantraniliprole against target pest species, based on time for feeding cessation and reduction in feeding damage, is significantly greater than that of most recently developed insecticides and comparable only with the speed of action of the fast-acting carbamates and pyrethroids. In addition, chlorantraniliprole has a favorable toxicological and ecotoxicological profile. It belongs to a new chemical class with a novel mode of action and is effective against insect populations that have developed resistance to other insecticide groups, thus representing an attractive new tool for integrated pest management programs.