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

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



Periscelis is usually found on trunks of rainforest trees. Cyamops often rests on damp stones in streams. Flies of these two genera generally only walk slowly forwards. Stenomicra includes curious flies that maintain a head-upwards position when on a vertical surface, but can run in any direction without turning (compare family Neurochaetidae). Various Stenomicra species (mostly undescribed) are associated with particular taxa of the Australian flora (author's observations), e.g. Alocasia (Araceae), Kingia (Xanthorrhoeaceae =Dasypogonaceae), Lomandra (Xanthorrhoeaceae =Lomandraceae), Musa (Musaceae - both native and cultivated), and Pandanus (Pandanaceae).


These small, slender and somewhat flattened flies have the following diagnostic features:

Face strongly sclerotised, convex or protuberant medially; orbital bristles one or two; antenna with pedicel dorsally slit; first flagellomere usually deflexed; arista with penultimate segment asymmetrical or absent; terminal segment long-plumose; fore coxa with basal membranous foramen not more than half as long as coxa.


The family has an extensive world distribution, but the majority of species live in the wet tropics. The genera Periscelis , Cyamops and Stenomicra have wide overseas distributions, but the 17 Australian species are probably mostly endemic.

  • Drawing of the head of a Periscelididae fly