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

Logo: What Bug Is That? Logo: Taxonomy Research & Information Network



The Bibionidae have the vernacular name of  'March flies' in some parts of the Northern Hemisphere, where the abundance of many species in spring time brings them to public attention. The North American names of love bugs or harlequin flies are no more appropriate.  The family is cosmopolitan, with some 700 extant species worldwide.

Although some Australian species may be quite abundant as soil temperatures increase following winter, clearly 'March' is a misnomer in the Southern Hemisphere.

The immature stages of Bibionidae are found in soil, where the herbivorous larvae can cause damage to roots of grasses in pastures, and certain other crops. They feed also on rotting vegetative material, such as compost,  manure and leaf litter, where they can attain high densities.


Adult Bibionidae are recognised by the presence of ocelli, and wing venational features, including the costa terminating close to the end of vein R4+5 near the wing  tip, with two branches of M, no more than three branches of R and with two closed basal cells. The antennae of Australian taxa are anteriorly directed and rather short, comprising round, compact flagellomeres.

Larval Bibionidae have a protruding complete head capsule, lack prolegs, and are holopneustic, lacking spiracles only on segments 2 and 8.


Bibionidae are worldwide in distribution, with the exception of Antarctica. Australian taxa belong to cosmopolitan Bibio and Dilophus in Bibioninae and Plecia in the Plecinae. If there are interesting distribution patterns in the austral bibionids, they are not revealed by the current taxonomic understanding.

  • Plecia ornaticornis

  • Bibionidae; Plecia sp. male

  • Bibionidae