The Cheilosiini are a small but distinctive tribe of hoverflies within the subfamily Eristalinae, best known for their wasp-like or sombre, non-typical syrphid appearance and their association with fungal habitats. Unlike the brightly marked flower-visiting hoverflies familiar to most observers, members of this tribe are generally dark, slender, and unobtrusive, often resembling solitary wasps or small empidid flies rather than typical syrphids. Their muted colours and secretive habits mean that many species frequently go unnoticed.

The tribe is centred primarily on the genus Cheilosia, one of the largest hoverfly genera in the Palearctic, with over 300 species. This makes Cheilosiini one of the most diverse lineages of hoverflies in temperate Eurasia. The adults typically have matte black, bronze, or dark grey bodies, sometimes with subtle dusting or weak abdominal patterning. Their faces tend to be more projecting than in other Eristalinae, and the antennae somewhat elongate. Wing venation follows the typical eristaline pattern, though the wings are often clearer and less patterned than in related tribes.

The larvae are the most distinctive aspect of the tribe. Many Cheilosia larvae feed in fungi, especially in the fruiting bodies of bracket fungi such as Fomes or Ganoderma. Others mine inside the tissues of various plants, including thistles, buttercups, saxifrages, and plantains, often producing characteristic galls or internal tunnelling. This combination of fungal and plant mining makes Cheilosiini unusual among hoverflies, whose larvae more typically inhabit decaying organic matter, aquatic environments, or aphid colonies. Because of their larval specialisation, Cheilosiini adults are often found in damp woodlands, shaded clearings, or along hedgerows where their host fungi or plants occur.

Despite their cryptic nature, adults do visit flowers, though they tend to prefer small, low-key blossoms such as umbellifers or composites, and they are more often seen basking on leaves or tree trunks. Their flight is light and agile but less hovering and more darting than in many other syrphids.

Taxonomically, Cheilosiini form a well-supported group within the Eristalinae, though the boundaries of some genera have historically been a matter of debate. Molecular and morphological evidence places them apart from the better-known drone-flies (Eristalini) and the saproxylic Brachyopini, reflecting their unique ecological roles