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

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In Australia this family is represented by Tasmanocoenis (5 spp.) (Suter 1984). Adults of Tasmanocoenis frequently swarm along the margins of streams in the early morning in temperate Australia. In tropical species swarming may occur at night at sites remote from water (Marchant 1982).


Like the nymphs of Tasmanophlebia , nymphs of Tasmanocoenis have an operculate abdominal gill covering the other gills, but in Tasmanocoenis it is the second gills rather than the first, and the operculate gills are fringed with fine hairs. Nymphs of Tasmanocoenis are also considerably smaller than those of Tasmanophlebia . Adults of Tasmanocoenis are small but distinctive; the sexes are alike, with eyes of similar size, and the hind wings are absent. The fore wings are broad and fringed with fine hair.


Nymphs are widespread in Tas. and the mainland, occurring especially in silty areas of stony streams or rivers, and also in standing waters. Their diet seems to consist mainly of fine detritus (Chessman 1986) and they are among the more pollution-tolerant of Australian mayflies. T. tillyardi in S.A. streams has 1 or 2 generations per year with multiple cohorts continuously present (Suter 1980; Suter and Bishop 1980). T. tonnoiri is bivoltine in the La Trobe R, while another unnamed species is univoltine (Marchant et al. 1984). For all 3 species the emergence period is spring-summer, and for the first 2, adults emerge for 5 months or more. In the tropical Magela Ck system, a species of Tasmanocoenis similar to T. tillyardi has a nymphal development time of about 4 weeks on average and as short as 2 weeks (Marchant 1982), with adults emerging year round.

  • Tasmanocoenis sp . nymph

  • Irpacaenis coolooli   nymph

  • Irpacenis deani  nymph

  • Tasmanocoenis sp.

  • Wundacaenis dostini  nymph