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.
Discerning from amongst these differences what the identity of the single blacklet hoverfly caught in a photograph is requires considerable experience and knowledge. Specialists will be able to narrow the identification down to a single species. The individual shown here on a Wild Carrot in late June might very well be Cheilosia pagana because of the colour of its legs, the fact that it has orange antennae, the shape of its face in profile, and its hairless eyes. ‘Might’ is the operative word in that last sentence! We can, however, be sure that it is a hoverfly of the Cheilosia genus.
For the super-keen, I recommend you visit the Flickr gallery of hoverfly photographs by Steven Falk, one of Britain’s foremost hoverfly experts. His gallery of photographs of the Chelosia genus of hoverflies is especially fine.