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

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Coelopids (Kelp Flies)  are inhabitants of sea shores and most species live among stranded kelp on beaches. Adults of some species may move to nearby sheltered rock surfaces, but rarely fly inland. Chaetocoelopa sydneyensis (Schiner) sometimes forms enormous aggregations on shoreline rocks or nearby shrubs or tussocks. Larvae of most species consume decaying kelp. When subject to removal from the beach by waves, larvae of some species can survive floating in the sea for several days.


Coelopid adults generally have the occiput flattened so as to fit closely to the thorax (possible streamlining), though the aberrant rock-living Lopa convexa McAlpine has a convex occiput. Further diagnostic features include:

Relatively complete venation, with vein C unbroken, vein Sc complete, and vein A1+CuA2 reaching the wing margin; antenna decumbent when at rest, with first flagellomere subcircular; terminal tarsomere subtriangular, with two or three setiferous tubercules on distal margin.
Larvae of all species have each posterior spiracle encircled by a series of plumose hydrofuge hairs.


Most world species are temperate in distribution. Thirteen species are recorded for the Australian fauna, more than for any other country, including two species on Macquarie Island.

Numerous species can be cultured in the laboratory and some have been used for genetic and behavioural studies.

  • Coelopidae

  • Coelopidae