Ephydridae (shore fly, sometimes brine fly) is a family of insects in the order Diptera. Shore flies are tiny flies that can be found near seashores or at smaller inland waters, such as ponds. About 2,000 species have been described worldwide, including Ochthera. The petroleum fly, Helaeomyia petrolei, is the only known insect whose larvae live in naturally occurring crude petroleum. Another notable species is Ephydra hians which lives in vast number at Mono Lake.