Biology and Immature Stages of Snail-Killing Flies: The Genus Elgiva (Diptera: Sciomyzidae)123

Larvae of Elgiva rufa (Panzer) (Holarctic), E. connexa (Steyskal) (Nearctic), and E. cucularia (L.) (Palearctic) are predators of aquatic, pulmonate snails belonging to the families Lymnaeidae, Physidae, and Planorbidae. Ecological distribution, mating, oviposition postembryonic development, larval feeding behavior, seasonal aspects, hymenopterous parasitoids, and other ethological and ecological characteristics are discussed. Descriptions and illustrations of the eggs, 3 larval instars, and puparia, and keys to larvae and puparia are given.