Truffle Blacklet

Adults hoverflies of this species are seen on umbellifers (as shown here) between June and early autumn.

Species introduction

At a glance
Latin name: 
Cheilosia soror
Family: 
Hoverflies
Family Latin name: 
SYRPHIDAE
Category: 
Insects other

Species description

Species description

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.

Species photographs

Larger photograph(s) (click to magnify)
Adults hoverflies of this species are seen on umbellifers (as shown here) between June and early autumn.

Details

Species family information

True to their name, the hoverflies hover around flowers, and then alight to feed on nectar and pollen. They are very important pollinators, and despite the fact that some look like wasps or bees, this is just mimicry and helps to keep potential predators at bay. Hoverflies have no sting, and have short, drooping antennae. The larvae are as useful as the adults, in that they feed on aphids. 

We have a photograph-filled blog post about all the hoverflies that we have seen in the Cemetery that may be worth your time.

Category information

Insects evolved in the Ordovician from a crustacean ancestral lineage as terrestrial invertebrates with six legs (the Hexapoda). This was the time when terrestrial plants first appeared. In the Devonian some insects developed wings and flight, the first animals to do so. An early flying group was the Odonata from the Carboniferous, the damselflies and dragonflies, which have densely-veined wings and long, ten-segmented bodies. They are day-flying carnivores, with an aquatic larval stage, so are commonly seen flying near water. The carnivorous larvae are called nymphs. Odonata species are short-lived, damselflies surviving for 2-4 weeks, dragonflies for up to 2 months.

Some insect groups in the Cretaceous co-evolved with the flowering plants, and they have had a close association ever since. These groups are the Hymenoptera (bees, wasps, and ants), the Lepidoptera (butterflies and moths), the Diptera (flies), and the Coleoptera (beetles). The diversity of beetles is astonishing. Of all the known animal species on the planet, one in five is a beetle!