Stoneflies

Stoneflies are a widespread group of invertebrates, found in most streams and rivers around the country. The adults live for about 20 days and are frequently found flying near vegetation alongside streams.

The image above was taken by Neil in October last year as he surveyed Risedale Beck. This naiad is the juvenile phase of the stonefly lifecycle and can take up to 3 years to develop into an adult. They ecdyse (shed their skin) up to 35 times during their development and when ready to emerge as an adult climb out of the water onto a rock or branch to shed their exoskeleton for the last time.

Stonefly exuviae were seen in large numbers on the section of willow spiling; after we had spotted these we noticed many adults were flying over and near to the beck.