is divided into four branches, all independent but with M 3 and M 4 convergent. The transverse medial vein closes the discal cell. This has an elongated shape and terminates at the apex with three angles from which the first three branches of media spring. The fourth branch, M 4 (or CuA 1 according to a different interpretation), originates from the apex of the posterior basal discal cell. The cubit and anal converge on a short common branch before reaching the apex. The larva is apodous and eucephalic, cylindrical, very long and thin, and with tapered ends. The integument is smooth, white, or pink. The head capsule is well developed, but narrower than the other regions. Biology Knowledge of the biology of the Therevidae is limited and fragmented. The lifecycle is usually carried out in a single generation per year, although some European Therevidae have a cycle of two or more years. The overwintering stage is represented by the mature larva. The postembryonic development in known forms, five instars and pupation takes place in the spring. The larvae, like those of other Asiloidea, have an entomophagous diet and they live as predators. They are generally found on dry, sandy soils and dry litter. Larvae also are located in other substrates such as decomposing organic matter and under the bark of trees. Among the prey are the larvae and pupae of Diptera, Coleoptera, and Lepidoptera. The observation of the behaviour of known forms highlights voracious feeding and agile movements. When exposed to light, the larvae of the Therevidae dig back into the substrate with rapid movements. Adults feed mainly on nectar, honeydew, and pollen, but they occasionally feed on liquid secretions of animal or vegetable origin. They are found in various environments and can be found in streams, meadows, open woodlands, or, like many other Asiloidea, in dry and sandy places or on beaches. At rest, they choose various substrates according to the species: some species rest on the ground, others on rocks, vegetation, or intertidal debris. They are generally diurnal and move in short, quick flights. Although inhabiting semiarid regions, or possibly for that very reason, since that is where prey for their larvae are likely to be plentiful, adults are particularly attracted to water, generally remaining near pools or other sources of moisture. Systematics and phylogeny The family Therevidae is little known and it resembles many other Brachycera, both