Larvae of the Asiatic clam,Corbicula fluminea, and their tissue products stimulated gluttonous feeding behavior in a predatory rhabdocoel turbellarian,Macrostomumsp. This gluttony resulted in death of the worms. I suggest that lethal gluttony may be induced by some prey species and serve as an altruistic mechanism sacrificing numerous individuals to eliminate predators and provide greater survival for the remaining prey. This mechanism may be advantageous especially to a species which is expanding its range into regions where it encounters potential predators for the first time. Lethal gluttony could eliminate the predator population before it adapts to the newly introduced prey.