Larvae of 2 closely related species of predators, a generalist, Chrysopa quadripunctata Burmeister, and a specialist, Chrysopa slossonae Banks, differed significantly in most of 14 morphological traits. In all instances the specialist predator had the larger structures (head width, mandible length and width, prothoracic sclerites, and tibial length). The pattern of variation among the F-2 progeny (parental genotypes and the primary and secondary hybrids) showed that most of the species-specific differences are polygenically based. Moreover; at least 2 of the traits are geographically variable in the generalist. We propose that the evolutionary diversification of generalist and specialist larval morphology occurred largely as a consequence of adaptation to prey.