Stiletto Fly

Very little is known of the ecology of this species. The larvae of all stiletto flies are soil predators, and it is presumed that those of Spiriverpa lunulata live in loose sand (3).

This stiletto fly is a UK Biodiversity Action Plan (UK BAP) priority species, and a Species Action Plan has been written in order to outline action required to conserve it, with the over-riding aim being the maintenance of all current populations (3). The organisation responsible for the delivery of these actions (the 'lead partner') is the Environment Agency. Future work on this fly will aim to determine the ecological requirements and distribution of the species more precisely, and to produce guidance on sympathetic river management (2). A number of known sites are Sites of Special Scientific Interest (SSSIs), and a few populations occur in candidate Special Areas of Conservation (SACs), including those on the rivers Usk and Tywi in Wales (3).

The stiletto fly Spiriverpa lunulata is a pale grey colour, and covered in fine downy hairs that give the fly a 'fluffy' appearance. The large eyes are a bronze-brown colour, and the legs are dark reddish-brown (2). Like all flies, this species has one pair of true wings; the second pair of wings are reduced to club-like balancing appendages called 'halteres' (4).

This stiletto fly is associated with sandy riverbanks, particularly where sand ridges build up (3). It needs open conditions, with no shading by trees (3).

In Great Britain, this species has been recorded from just a handful of sites in Scotland, the north of England, and south and west Wales (3). Recording effort has been greatly increased recently, and a few new sites have been discovered, but some existing sites are threatened. In Europe, this fly has a wide distribution, but its status is unclear in many countries (2).

Classified as Rare in Great Britain (3).

The threats facing this species include the removal of sandy sediments from rivers for aggregates, and the deepening and canalisation of rivers (3).

Spiriverpa lunulata is a Palearctic species of stiletto fly in the family Therevidae.