Commonly known as the Large Dark Olive mayfly, this species is part of the mayfly family that are characterised by the adults having two cerci (tails), small oval hindwings and short veins visible between the long veins of the forewings. This species is one of the earliest mayflies to hatch and one of the biggest. As many as 4500 eggs are laid on a submerged stone within a moving body of water such as a river or stream. Once the larvae hatch they live amongst the sand and gravel where they scrape algae off of submerged stones and collect organic materials from the water bed for food. The species is frequent and widespread across Britain and particularly common in Leicestershire and Rutland.