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Ecdyonurus dispar (Autumn dun)

Ecdyonurus dispar is typically found in riffle areas of rivers and larger streams.  It can also occasionally be found on the wave-lashed shores of larger standing waters.  The nymphs are usually found clinging to submerged plants and stones, although they may swim if disturbed.  E. dispar feeds either by scraping periphyton from the substrate or by gathering fine particulate organic detritus from the sediment. 

 

There is one generation a year, which usually overwinters as nymphs and emerges between June and October.  Males may be found swarming throughout the afternoon. 

 


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Once mated, the female rests on a stone above the water and lays around 2500 eggs directly on the river bed by dipping the tip of her abdomen under the surface.

 

Due to the problems with identification of nymphs, it is difficult to compile a complete distribution for this species.  E. dispar is however, thought to occur in suitable habitats throughout the UK and Ireland.