Plecoptera

Plecoptera are found in pristine freshwater habitats and most species of stoneflies are intolerant to water pollution and negatively affected by most artificial methods of flow regulation. Their presence and species diversity can often be used as indication of good or excellent water quality. The immature stages, called nymphs, display a wide range of body sizes (body length: 0.4 - 50 mm) and occur in all cool and clean freshwater systems but also underneath rocks in cold-temperate rain-forests of the Southern hemisphere. However, most species prefer coarse gravelly, fast flowing creek sections, where they can also be found deep in the interstices of the hyporheic zone.
  The nymphs have a slightly flattened and elongate body with two, usually long cerci. The body is usually brownish or greyish in colour. Plecoptera nymphs display a wide range of feeding habits, with species preying on algae and particulate organic matter while others also prey on a wide range of aquatic invertebrates including benthic rotifers and larval chironomids2-4. Nymphal stoneflies are also prey for other aquatic invertebrates, fish and birds.
  The winged adults resemble the nymphs, and are found among waterside rocks and/or vegetation.