This small, nearly completely black hoverfly is an excellent example of hoverfly diversity. Whilst there may be in the region of 280 - 285 British hoverflies, there are perhaps 40 different hoverflies in the Cheilosia genus, the largest genus of them all. In Europe as a whole, there may be as many as 135 species within the Cheilosia genus of hoverflies. Where bird-watchers call the many small brown passerine birds ‘little brown jobs’ (or LBJs), hoverfly aficionados call these Cheilosia hoverflies ‘little black jobs’.
Colloquially named the ‘blacklets’, these hoverflies range in size from about 5 mm to no more than 11 mm. Most are more or less uniformly black, and the differences between them are miniscule. Some have abdomens with grey rectangular dust markings, some have grey thoracic stripes, a few have orange antennae (with or without thoracic stripes), some have mouth parts that protrude into a beak shape (specialized for feeding on plants like Red Campion), others have a vaguely orange abdomen, and some have furry bodies while others have few or even no bristles. Their general blackness remains the constant.
This individual is the Truffle Blacklet (Cheilosia soror). This precise identification is aided by the fact that this photograph shows the rear tip of the insect’s scutellum (the small semicircular plate between its thorax and abdomen) as having an orange-coloured edge. This marks out the three members of the Cheilosia family of hoverflies as having been reared by their parents from truffles.
The Truffle Blacklet species is found in chalk and limestone districts in southern Britain, particularly calcareous grassland, scrub and woodland. It is slightly out of its range here in Worthing.
Adults are seen on umbellifers (as shown here) between June and early autumn.