Naturalised in aquatic nurseries through accidental introduction in aquatic plants from the Far East. First discovered in Britain at Enfield, Middlesex in 1978. Not recorded in Hampshire or on the Isle of Wight to date. Wingspan male 11-14 mm, female 16-22 mm. The darkest and largest of the Nymphulinae which frequent aquatic nurseries. Larva feeds on various aquatic plants, living entirely underwater, causing sufficient damage to be a serious pest in some areas.