Order Plecoptera - Stoneflies

• Perla burmeisteriana

Soft-bodied insects with long thread-like antennae and cerci. Weak biting mouthparts. Wings membranous, hind pair usually larger than front pair, and folded flat over the body at rest. Simple metamorphosis, with over 30 nymphal moults before the adult stage in some species. The nymphs are aquatic, often with filamentous tufted gills on various parts of the body (usually near the bases of the legs and cerci), although they obtain much of their oxygen by simple diffusion through the whole body surface. Stoneflies are a relatively small Order with about 3,000 known species, of which only 34 occur in the British Isles.

Description. One of the larger stoneflies, almost 30 mm long, brown in colour.

Biology. Found near clear streams and rivers. Adults probably need very little nourishment and may not feed at all. The nymphs are predatory and feed chiefly on the larval stages of other aquatic insects. Development probably takes two to three years.

Distribution. Central Europe.

Photos: V.J. Stanek ©

Nymph

Adult