DIPTERA > BRACHYCERA | Higher Diptera

MUSCOMORPHA > SCHIZOPHORA > Acalypratae > Opomyzoidea > Clusiidae (10 species)

(subfamilies: Clusiinae and Clusiodinae)

Small to medium-sized (3-8mm) relatively slender flies with a dull to lustrous, yellow to dark brown or black body, and wings that often have a slightly smoky appearance especially at the tips. The adults are mostly seen around decaying tree trunks in damp coniferous woodland.

The British List recognises ten species, three of which are only found in Scotland and two others are rarely recorded. A further species, Clusiodes ruficollis, is mostly confined to central England and Wales, which leaves four species that could possibly be encountered locally. They have all been recorded in Dorset at some point, but in total there are very few confirmed records. The last official record for the featured species was way back in 1998.

The most frequently observed species are Clusiodes albimanus, Clusiodes verticalis and Clusia flava.

Clusiodes albimanus and Clusiodes verticalis have all their orbital bristles backwardly-directed, a feature that if clearly visible in photos distinguishes them from the only other Clusiodes sp. that could be seen locally, Clusiodes gentilis, which has convergent lower front orbital and forward-directed outer orbitals. Similarly, Clusiodes verticalis can be separated from Clusiodes albimanus by having two rather than three orbitals and no post-verticals.

Clusia species have crossed front orbitals and white halteres. More specifically, Clusia flava, has no post-verticals or pre-scutellar bristles, but does have posterior pre-scutellars, which are convergent and crossing. Additionally, and hopefully more visual in photos, the wings have a vague cloud towards the front and over cross-vein m-cu. If by chance you encounter an individual with three clouded areas on the wings that looks a bit like a sepsid fly then it could possibly be the only other species in this genus, Clusia tigrina. There are only a handful of confirmed sightings of this species according to the NBN Atlas, but a couple have been recorded in the New Forest in recent years, so it can't be ruled out.

July 24