BRACHYCERA, Muscomorpha Schizophora Calyptratae, Oestroidea
Number of British species: 60
Small to very large (3-22 mm), usually stout and bristly flies. Most species grey to greyish black with a characteristic, shifting, checkered pattern on their abdomen; some species yellow-grey, green-grey or almost entirely black lustrous, never metallic blue or green. Arista bare to plumose. Wing usually hyaline, sometimes infuscated anteriorly or variously ornamented with dark markings; vein M1 always curving forward, sometimes ending in vein R4+5 at the wing margin or before, making cell r4+5 petiolate. Lower calypter usually broadly rounded-triangular, in a very few cases smaller and more or less round to elliptical. Subscutellum narrow and flat, not swollen; meral bristles always present; posterior spiracle covered by an anterior and posterior lappet, usually the anterior lappet a narrow fringe and the posterior one forming an operculum.
The life mode of the larvae is most variable: brood parasitoids of Hymenoptera such as Sphecidae, Pompilidae and, in the Miltogramminae, Apoidea; feeding on excrement (coprophagous larvae); inquilines preying on larvae and pupae of bumblebees and social wasps; feeding on carrion (necrophagous larvae) of fish, crustaceans, amphibians, reptiles, birds and mammals; necrophagous with all transitional stages into endoparasitism on grasshoppers, beetles and caterpillars and pupae of butterflies, on true bugs (Hemiptera), sawflies and wood wasps (Hymenoptera: Symphyta), on centipedes and millipedes, on earthworms and snails; parasitoids in pupae of Lepidoptera and Hymenoptera: Symphyta, on egg clusters of grasshoppers and spiders, on eggs of reptiles (including those of lizards); facultative and mandatory agents of myiasis in vertebrates and man. Adults can be found in a wide range of habitats; some species prefer coastal habitats. The males in particular often visit flowers.