Lejops vittatus (Meigen, 1822)
Helophilus vittatus Meigen in Coe (1953).
Biology & ecology:
There is a continental account of larval development; eggs are laid on the stems and leaves of emergent vegetation and larvae remain amongst surface vegetation until the last instar, at which point they migrate to submerged organic deposits. In Britain the majority of localities are permanently wet grazing marsh ditches with stands of Sea Club Rush Scirpus maritimus and with fluctuating levels of brackish water. Adults are known to feed on pollen from the flower heads of Sea Club Rush and can occasionally be found in numbers by sweeping.
There are records from the south and east coast, from Norfolk to Sussex. It also occurs on the grazing marshes of the Gwent Levels and Somerset. Very old records from inland localities suggest more widespread distribution in the past. There are post-1990 records from Norfolk, South Essex, East Kent, East Sussex and Somerset Levels, with the bulk of records from East Kent.
Status & conservation:
The frequency of occurrence suggests a decline, but there has been very little recording effort in grazing marsh since the late 1980s. It is therefore likely that it is under-recorded.