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

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The adults are slender, delicate flies recognised by the wing having a large anal lobe, and reduced number of main veins, but with a network of creases in the intervening spaces. The characteristic wings have given rise to a vernacular name of 'net-veined midges'.

The Blephariceridae are cosmopolitan. Some 270-300 species are described, with the relatively well-studied Australian representatives displaying some interesting biogeographical patterns. Blephariceridae are generally absent from oceanic islands.

The Blephariceridae are restricted in all stages to the immediate surroundings of rocks and boulders in fast-flowing waters, including torrents and waterfalls.

Adults do not swarm, but cluster underneath rocks, fallen logs, etc, close to their emergence site. Mandibulate females may prey on adults of other aquatic insects, the diet of males and non-mandibulate females is unknown.

Eggs of Blephariceridae are laid on smooth rocks and boulders alongside or within fast to torrential waterways, usually as the water is dropping in spring. When the water level rises again, hatching takes place and larvae adhere tightly to the surface with their flattened bodies and ventral sucking organs. Feeding is by grazing of diatoms, micro-algae, etc, on rock surfaces. Pupation is rapid, and seems more prevalent in the thin water film at the edge of the torrent than within the current.


The very distinctive larvae of Blephariceridae are unlikely to be mistaken for anything else although it may be difficult to recognise them as Diptera, due to their extensive modification. The body is very dorso-ventrally flattened and distinctly lobed. The first (anterior) division of the body, the cephalic, comprises the fused head, thorax and first abdominal segment; the five posterior lobes represent abdominal segments. The terminal division represents the fused abdominal segments 7-10.


This family displays conventional South American Gondwanan connections, and others showing an arguable dispersal route both into and out of the Oriental Region. Whether or not there is a named fossil record of Blephariceridae depends upon interpretation of some equivocal Eocene fossils. However, unnamed taxa do occur in the Cretaceous.

  • Blephariceridae larvae

  • Blephariceridae

  • Blephariceridae

  • Blephariceridae pupae on rock