Stoneflies

Code QP999999

See Key to Families of Australian Aquatic Plecoptera Larvae

A minor and often cryptic order of insects, with perhaps 2,000 species worldwide, predominantly in temperate and cool areas. Hemimetabolous, with adults resembling winged nymphs. Adult mandibulate with filiform antennae, bulging compound eyes and 2-3 ocelli; thoracic segments subequal; fore and hind wings membranous and similar, except hind wing broader, with folded wings partly wrapping abdomen and extending beyond abdominal apex, although aptery and brachyptery frequent; legs unspecialised, tarsi 3-segmented; abdomen soft, 10-segmented, with vestiges of segments 11 and 12 as paraprocts, cerci and epiproct, a combination of which serve as male accessory copulatory structures sometimes in conjunction with abdominal sclerites of segments 9 and 10.

Nymphs with 12-24, perhaps as many as 33, aquatic instars; with fully developed mandibulate mouthparts; wings pads first visible in half-grown nymphs; closed tracheal system with simple or plumose gills on basal abdominal segments or near anus, sometimes extrusible from anus, or on mouthparts, neck, thorax, or lacking; cerci usually multisegmented, no median terminal filament.

Nymphs may be omnivores, detritivores, herbivores or predators. Adults feed on algae, lichen, higher plants and/or rotten wood; some may not eat. Mature nymphs crawl to water's edge where adult emergence takes place. Nymphs occur predominantly on stony/gravelly substrates in cool water, mostly in well-aerated streams, with fewer species in lakes. Generally very intolerant of pollution.