Mayfly Ephemera danica
Length Up to nearly 2 cm in size,
Description A large species with three tails and large hind wings. The sub-imago (immature adult) has grey wings, with a yellowish green tinge and heavy venation. The body is creamy yellow with distinctive brown markings on the body segments. The tails are dark grey black and the legs are a creamy olive colour with black markings. In general, the colours of the wings, tails and legs are darker, and the body paler in the male. The imago (fully mature adult) has transparent wings, which have heavy brown venation and several dark patches. The body is creamy white with the last three segments brownish. The tails are extremely long and almost black in colour.
Life Cycle Nymphs live in lakes and fast flowing rivers and streams with a sandy or gravely bed. The nymphs dig into the gravel to form a tubular burrow and they use their gills to force the water through this burrow. The nymphs feed by filtering or collecting fine particulate organic detritus from the water column. Ephemera danica usually has a 2 year life cycle; recent work has shown that in the warmer waters of S England it is able to complete its life cycle in one year.
Habitat Around unpolluted lakes and fast flowing rivers and streams, especially those with a sandy or gravely bed.