Helophilus trivittatus (Fabricius, 1805)Nomenclature
Helophilus parallelus (Harris, 1776) in Kloet & Hincks (1976).Biology
Larva not described, but has been reared in captivity from eggs laid on an infusion of hay in water and from larvae found in semi-liquid mud mixed with animal dung. Speight (2010) describes it as a species of open wetlands including river-margins, seasonally flooded grassland and saltmarsh. Adults are found visiting a wide range of flowers, not infrequently well away from sites suitable for breeding and very often on dry grassland sites.Distribution
This is a very widespread but usually infrequent species, found only as single specimens. There is no obvious association with any particular habitat, but many records are coastal and there is a possible link to river valleys as illustrated by the concentration of records within the Severn valley. It is regarded as a migrant in continental Europe and the pattern of distribution in GB suggests that some records are likely to represent immigrants. Records have become more frequent since 2000.