What Bug Is That? The guide to Australian insect families.

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Ephydrids live in diverse habitats, including forests and grasslands, particularly where these include damp patches or impinge on swamps; but the most characteristic habitats for many species are margins of salt swamps or other saline areas. Hydrellia tritici Coquillett, one of the most abundant flies in temperate Australia, has no preference for saline areas.

Some ephydrid adults are attracted to flowers for feeding. Larvae of many ephydrids are algal feeders on or in wet sand or mud, or on floating algal mats. Some, including Hydrellia , mine leaves or stems of aquatic or land plants, and others feed on carrion, most often of invertebrates.


These flies are mostly small to minute ( Dryxo are quite large), and have the following features:

Postocellar bristles absent, but sometimes a pair of divergent pseudopostocellar bristles  present close behind ocelli; vibrissa distinct or not so; face sclerotised, generally convex, sometimes very broadly and conspicuously so; antenna with pedicel dorsally slit; arista 2-segmented at most, often unipectinate, i.e. with a single row of long dorsal hairs (rays), but no ventral ones, or simply pubescent, or, rarely, vestigial; anepisternal bristle and katepisternal bristle usually present; prosternum broad, with precoxal bridge; tibiae usually without definite preapical dorsal bristle; wing vein C with subcostal break and generally with humeral break; vein Sc very incomplete distally; cells bm and dm confluent; cell cup absent or very incompletely enclosed; vein A1+CuA2 usually absent.


The Ephydridae are among the commonest of fly families worldwide. Around 100 species in the subfamilies Ephydrinae, Gymnomyzinae, Hydrelliinae, Ilytheinae and Risinae live in Australia. Many recent papers on taxonomy include Australian species, particularly those by I.R. Bock, W.N. Mathis and T. Zatwarnicki, but there is no general treatment of our fauna.

  • Rockhole fly

  • Rockhole fly

  • Ephydridae

  • Hydrellia sp.

  • Ephydridae, tiny shore fly