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Stoneflies, mayflies and caddisflies - river flies

These invertebrates includes several groups of insects which spend most of their lives as larvae on our river and loch beds. They provide a food supply for fish and birds, such as the dipper, and are an essential part of their environment.

Mayflies are some of the oldest winged insects known, dating from over 300 million years ago. There are around 3,050 species known in the World of which 51 species are known in the British Isles. Mayflies are the only insects to have a two-winged adult stages.

Stoneflies are a small group of aquatic insects, which generally prefer stony, fast flowing streams. There are 34 British species, including one species, the Northern February red (Brachyptera putata), which is only found in Scottish watercourses.

The Trichoptera, or Caddisflies, resemble moths. The name means 'hairy-winged' and ,indeed, they differ from moths in having hairs rather than scales on their wings, amongst other differences.  There are just under 200 species in the British Isles.