Naturalised in aquatic nurseries through accidental introduction in aquatic plants from Singapore. Abundant in aquatic nurseries at Enfield, Middlesex from 1977 since when periodically controlled by fumigation, also in other nurseries, and in many parts of Europe and the U.S.A. In Hampshire one was found dead in a striplight insect trap at Barton Stacey in July 1977. Not recorded from the Isle of Wight to date. Wingspan male 13-16 mm, female 17-19 mm. Similar to P. obscuralis
, which see. Larva feeds on water plants, living entirely underwater, causing sufficient damage to be a serious pest in some areas.