Tethina is a genus of beach flies in the family Canacidae (formally Tethinidae).

They are found in all terrestrial biogeographic realms.

[3] Like most Tethininae, Tethina species mostly live in salty environments.

They are found on coastal marine habitats including the intertidal zones and on wrack heaps, as well as salt marshes, coastal dune vegetation, and on salty soils or bare sand.

Some species of Tethina are also found at desert oases.