A fairly large species of mayfly with a yellowish body and a brown-reddish stripe running along its back. Each section of the abdomen is marked with small black dots. It has three long whip-like tails and large hindwings. The eyes are yellowish-green. Forewing 15 to 20mm.
They breed in fast-flowing water. The nymphs overwinter. They feed mainly on plant detritus.
It flies June to July. The nymphs and adults of this species live in and around the margins of large rivers. A very rare and localised species.
Photographs taken August 2011, rear garden, Staffordshire.