Bee-fly guide: revised version now available

The recording scheme guide to bee-flies in genus Bombylius has been updated to provide some more information on how to distinguish the two clear-winged summer bee-flies: Western Bee-fly Bombylius canescens, and Heath Bee-fly Bombylius minor. (The section on the two pattern-winged spring bee-flies remains unchanged.)

As shown in the guide, the most reliable distinction between the two summer species is to check the hairs between and behind the eyes: Western Bee-fly has mostly dark hairs, while the much rarer Heath Bee-fly has whitish hairs. This is not always easy to see on a live specimen, especially if it won't sit still! But if you can get a good close-up view from the side or from above it should provide a clear distinction.

Summer bee-fly identification image

There is also a difference in the colour of the femora (the first main segment of the legs, nearest the body), which are dark in Western Bee-fly and pale in Heath Bee-fly, but this is a much less clear-cut distinction, because A) when fresh, both species have pale scales on the legs that can obscure the underlying colour of the femora; B) Western Bee-fly often has the tips of the femora paler than the rest, and since it is usually the tips that can be seen unhidden by the body this can mislead; and C) when taking photographs it is very hard to get a true representation of the colour of the femora, partly because the femora are often in shadow under the body.

Location, habitat and time of year are all good clues as well:

  Western Bee-fly Heath Bee-fly
Location South-west England and south Wales Only known from south Dorset heathlands and sandy coasts on the Isle of Man
Habitat Various flower-rich habitats including grasslands and river valleys Sandy soils, on heathland or by the coast
Time of year Mainly flies from mid-May to early July Mainly flies from early July to mid-August

There is a bit of overlap in flight times around the beginning of July, and since bee-flies can fly (!) there is always a chance that one could turn up in the other's habitat, but there are no known sites where both species occur.

Since Heath Bee-fly is so rare, any records need to be supported by good evidence such as a close-up photo (this is essential for records away from the two known locations).