Small to large flies, 2.5-21 mm long. Head small to medium-sized, consisting mostly of large compound eyes. Abdomen globose, globose-elongate, or narrow and tapering or parallel-sided; color dull or shiny and often bright metallic green, blue, red, or purple, or sometimes brown, black, orange, yellow, or white with maculations on abdomen and with vittae on mesonotum. Some species bee-like, others wasp-like, and some even beetle-like, many appearing to be mimics. Family characterized by following combination of morphological structures: three-segmented antenna, small head, large calypter, pulvilliform empodia, simple unbranched R2, and body without bristles.