The Cry9Ca1 toxin from Bacillus thuringiensis was significantly more toxic to spruce budworm (Choristoneura fumiferana) than the Cry1Ab6, Cry1Ba1, Cry1Ca2, Cry1Da1, Cry1Ea1, and Cry1Fa2 toxins. It displayed high activity against silkworm (Bombyx mori) but was not toxic to black army cutworm (Actebia fennica) or gypsy moth (Lymantria dispar). The Cry9Ca1 is the most effective spruce budworm toxin known to date and may offer promise for control and resistance management of that species.