Rather small, narrowly-built hoverflies typically with yellow, orange or grey-spotted abdomens, a dark scutellum (unlike similiar-looking genera such as Melangyna, Meligramma and Meliscaeva) and male forelegs obviously modified through being broadened and bearing hair tufts, fringes or other strange bristles. Melanostoma species, especially M. mellinum, can resemble species like P. angustatus in the field but have totally unmodified front male legs, females with triangular spots on tergites 3 and 4 and a highly reduced metasternum between the mid and hind coxae.
Twenty-five species are currently known from Britain, two of which (granditarsus and rosarum) were placed in the genus Pyrophaena (now a subgenus of Platycheirus) until recently and look rather different. This genera has produced more new British species in recent years than any other, primarily through the splitting of the old concept of 'clypeatus' into 4 species, and the old concepts of 'peltatus' and 'scutatus' each into 3 species. Some of these new species were discovered on the basis of British rather than European material e.g. aurolateralis and spendidus. A further 26 species occur on the continent.
Platycheirus species appear to all have aphidophagous larvae. The males of some species undertake protracted hovering, notably members of the peltatus group (over low herbage) and ambiguus (beside Blackthorn blossom).