The Nematocera (nemato = thread and cera = horns; referring to the long, segmented antenae that are typical of this order) represent a group of flies that are important, for the most part, in feline medicine as the vectors of disease. These flies tend to be small and delicate. Only the females of this group require blood or tissue fluids from a vertebrate host; the males feed on nectar. The eggs are typically laid in water or semiaquatic habitats. The larvae undergo several molts and then pupate. The adult fly emerges from a longitudinal slit along the dorsal surface of the pupal case in the area overlying the thorax. The families tht are important in feline medicine include: the Culicidae (the mosquitoes); the Psychodiedae (the "sand” flies), the Ceratopoginidae ("no-see-ums”), and the Simuliidae (the black flies).