| Plecoptera (stoneflies) |
| Major Group: Insecta Order: Plecoptera Plecoptera are a small group of insects with the four families found in Australia all being restricted to the southern hemisphere. All Australian species are endemic. Adults are poor inactive fliers that live for only a few days to a few months feeding on algae, lichen, rotting wood and detritus. They are generally dull coloured and well camouflaged on rocks and vegetation bordering streams, but the large Eustheniidae species display bright colours when their wings are opened. Plecopteran nymphs are eaten by predators such as the larger dragonfly nymphs (Odonata), larvae of water beetles (Coleoptera), caddisflies (Trichoptera), other stoneflies and fish, (particularly mountain trouts). |
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| Ecology: Instream habitat: Stonefly nymphs generally occur in clear cool, running waters at high altitudes, sometimes being found on the edges of lakes at the point of inflow. Notable exceptions are Gripopterygidae: Dinotoperla serricauda, found in a cool lowland settlement pond and Dinotoperla evansi, found in farm dams in South Australia. Several species of Austroperlidae: Cosmioperla, Notonemouridae: Notonemoura and Gripopterygidae: Riekoperla can move into damp terrestrial habitats or burrow into the stream bank if the stream dries out. Feeding ecology: Plecopteran nymphs are mostly herbivores and detritivores, feeding on algae, leaves and detritus. However, Eustheniidae species are predominantly carnivorous, feeding on smaller invertebrates, and some Gripopterygidae species are omnivorous. Habit: Many stonefly nymphs have flattened bodies as an adaptation for living on stones in fast currents. They extract oxygen from the water generally by way of anal or lateral gills. Life history: Stoneflies can only breed in cool clean water. When stonefly adults mate, the male mounts the stationary female, mostly during daylight. There is no other distinctive mating behaviour. Females lay eggs either by sitting on a leaf and dipping their abdominal tip into the water flow, washing away non sticky eggs that will lay loose on the substratum, or crawling underwater, spreading sticky coated eggs on the underside of stones, or lodging a solid mass of eggs into a rock or log crevice. Females may lay singular eggs or batches of 100 up to 1000 eggs of variable shape. Early instars take a few weeks up to one year to hatch. Gripopterygidae: Dinotoperla bassae can have an eighteen month, or more, egg diapause during dry periods. Stoneflies go through ten to fourteen nymphal instars to reach maturity. Adult emergence usually occurs at dawn. The whole plecopteran life cycle can take from several months to several years. Most Notonemouridae species and the smaller species of Gripopterygidae have annual life cycles. It is probable that the alpine species of Eustheniidae has a longer life cycle. |
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| Information Sources: Theischeinger 1991, Williams 1980, Hadlington & Johnston 1999, Ingram et al 1997, Zborowski & Storey 1995, Sloane & Norris 2002 | ||||||
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