Family BLEPHARICERIDAE Loew, 1861

Blephariceridae

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Family BLEPHARICERIDAE Loew, 1861

Compiler and date details

September, 2011 - Kathleen Nugent & Christine Lambkin, Queensland Museum, Brisbane, Queensland, Australia

E.-M.E. Bugledich, CSIRO Entomology, Canberra, Australian Capital Territory, Australia

Introduction

The Blephariceridae are restricted in all stages to the immediate surroundings of rocks and boulders in fast-flowing waters, including torrents and waterfalls. The adults, which are slender, delicate flies, are 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'. Adults do not swarm, but cluster underneath rock, 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.

The larvae of Blephariceridae are very distinctive and unlikely to be mistaken for anything else but it may be difficult to recognise them as dipteran, 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.

Eggs of Blephariceridae are laid on smooth rocks and boulders alongside or within fast to torrential waterways, usually as the water level 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, microalgae, 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 Blephariceridae are cosmopolitan, although generally absent from oceanic islands. Some 270–300 species are described, with the relatively well-studied Australian representatives displaying some interesting biogeographical patterns. These include 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.