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Potamanthus luteus (Yellow mayfly)

Potamanthus luteus is a very rare species with most recent records from the Rivers Usk and Wye in Herefordshire.  It is thought that this species has since been lost from the River Usk and has recently suffered a population crash on the River Wye.  Nymphs of this species live chiefly in the pools and margins of larger rivers.  They are poor swimmers that typically live amongst stones and sand in side pools.  The nymphs feed by gathering fine particulate organic detritus from the sediment. 

 

There is one generation a year, which overwinter as nymphs and emerges between May and July.

 


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Emergence of the adults typically takes place on the surface of the water or partially or entirely out of the water on a stick, stone or plant stem at dusk.