Bee mimic flies in to a garden near you

25 April 2011

It’s hairy like a bee, hovers and hums, and has a scary looking spike at one end! The large bee-fly is making its springtime appearance in parts of the UK and causing curiosity at the Natural History Museum’s Identification and Advisory Service (IAS).

People have seen the strange looking creatures darting around flowerbeds and are wondering what they are and if they sting.

‘One of the first signs of spring for the Identification and Advisory Service is a wave of intriguing descriptions of a mysterious garden visitor,’ says Hannah Cornish, identification and advisory officer in the IAS.

A type of fly

They may look like a cross between a bee and a giant mosquito, but these insects are a type of fly called a bee-fly, in the family Bombyliidae. Flies have only a single pair of functional wings, whereas bees have 2 pairs.

Harmless to humans

The large bee-fly, Bombylius major, has a long, slender tongue called a proboscis, which looks frightening to some. But bee-flies are harmless to humans. They do not bite or spread disease and their proboscis is for reaching flower nectar to feed on.

Look out now

On warm sunny days, keep a look out as you may see the small furry insects darting and hovering around low growing flowers like primrose, bugle or violet.  

A bugle plant. This low-growing flower, with others like violet and primrose, attractive to bee-flie

A bugle plant. This low-growing flower, along with other such as violet and primrose, are attractive to the curious looking bee-flies. © Jörg Hempel /Creative Commons Attribution-Share Alike 2.0

Bee-flies hum and hover in front of flowers like bees. Unlike bees, however, when they feed they perch themselves on the flower with delicate long legs.

Nine species in the UK

Bee-flies are increasingly common in gardens and towns. There are 9 species in the UK and the one that you are most likely to see now is the large bee-fly, Bombylius major. It has a strong dark mark across the front half of its wings.

The wings are a good way to tell the difference between species. If you spot a bee-fly with a spotty wing edge, it is likely to be the rarer dotted bee-fly Bombylius discolor.

The adults of other bee-fly species appear later in the summer. For example the adults of the tiny Phthiria pulicaria, which are widespread on sandy coastal areas around Britain, are seen from June to August.

Other than B. major and P. pulicaria, most of the other bee-flies are rare and two, B. discolour and B. minor, have UK Biodiversity Action Plans to try and help protect them.

Parasite

Bee-flies may be harmless to humans but they are not so with other insects. Adults fly close to the ground searching for nests of solitary bees, wasps and beetles.

When they find one, they hover near the nest entrance and dip their abdomen into the surface of the soil to lay their eggs. The hatched larvae eats (parasitises) the bee, wasp or beetle larvae.

The rare species B. canescens has an interesting way of getting its eggs into nests. Museum fly expert Erica McAllister, who writes a blog about her work at the Museum, explains. 

'What I love about this species is that the females have been observed ovipositing (laying their eggs) by flicking their egg over or into burrows of bees with their legs! Wouldn’t that be a sight!’

Little known ecology of bee-flies

Very little is known about the ecology of bee-flies. There have not been many recent studies and a lot of information about them is anecdotal, says Erica. ‘Due to the rarity of many of the species things such as mating, hosts, flower-feeding, and life cycle development are poorly, if at all, known.’

New species settled in UK?

Last year a possible new bee-fly arrival in the UK was reported. A member of the public posted an image on the iSpot identification forum and it was identified as the European species Systoechus ctenopterus by a bee-fly expert.

The adult was in very good condition. Migrant species to the UK will often look more dishevelled from being blown in, or accidentally transported in, from outside the UK. So this suggests the bee-fly emerged in the UK and that there could be a breeding population.

Help with identifying bee-flies

The Museum’s NaturePlus identification forum is a good place to get help identifying bee-flies as you can post photos you have taken and experts will post replies.

Also in NaturePlus is the Curator of Diptera's blog by Erica McAllister. She has posted photos of the 9 species, and the newly arrived species, that occur in the UK.

Share this

Identification forums

Red-headed cardinal beetle, Pyrochroa serraticornis

Share identification tips on UK plants, insects, animals, rocks and minerals.  Museum experts will help to answer your queries and identify your specimens.

Natural History Museum's identification forums

Share this
Angela Marmont Centre for UK Biodiversity 
Angela Marmont Centre for UK Biodiversity

Discover the Centre for UK Biodiversity. It offers a drop-in identification service,  research facilities, and online nature resources. Watch a video and meet the team.

Find out about the Centre for UK Biodiversity