Fannia is a very large genus of approximately 288 species of flies.

The genus was originally described by the French entomologist Jean-Baptiste Robineau-Desvoidy in 1830.

A number of species were formerly placed in the genus Musca.

[3] The adults have plumose arista, with the first pre-sutural dorsocentral bristle over half as long as the second.

Males without a lower orbital bristle.