Xylocoris flavipes(Reuter) was shown to have the potential of being an effective predator of the red flour beetle,Tribolium castaneum(Herbst). Under all test conditions the predator killed more eggs than larvae or pupae of the red flour beetle. The mean maximum numbers killed during the lifetime of the predator were 539 eggs, 34 larvae, or 14 pupae when the stages of prey were available separately; the mean minimum numbers on which at least 46% of the predators survived to adulthood were 40 eggs, 9 larvae, or 6 pupae. When all stages ofT. castaneumwere available,X. flavipeskilled a maximum of 405 eggs, 4 larvae, and 8 pupae; the minimum numbers killed were 6 eggs, 2 larvae, and 6 pupae.