The larvae of this mayfly is about 1 cm long and patterned with light and dark browns, it has a large rounded head and upward facing eyes. There are three long tail filaments. Nymphs are described in Identification Aids below.

The larvae live on the underside of rocks in clear streams

Usually seen between summer and autumn

A study of nymphs has shown the presence of two definite broods of flies a year. The first swarms appear in June, the second from July to October. The early summer eggs hatch and emerge as flies within two months, whereas the autumn ones grow much more slowly and emerge the following June.

Thought to be fairly common in Britain, although most records are from northern and western regions.

Fairly common in Leicestershire and Rutland.