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Bee flies

Posted by Erica McAlister on Apr 12, 2011 9:21:18 AM

This week's blog I thought that I would write something bee flies. I am writing this for two reasons: one, they are often the first indicators of spring and two, a new species of bee fly has turned up in the UK. 


A couple of months ago I was on my way home listening to a pod cast when David Gibbs came on discussing these lovely flies. Now David knows a lot about these flies and proceeded to inform everyone of a new recording of a beefly species in the UK; this was important for two reasons, (1) it’s a new fly, bee fly at that, and they are great!, and (2) the identification came from an iSpot identification (more about this in a bit)!


We often get migrant species in the country - blown over the channel, hitching a lift on another animal or with us - but this one was very different and that is why it was more exciting. This one was in very good condition indicating that it had emerged as an adult here and so there may be more of them ...


So I am talking about Bombyliids, or Bombyliidae to be more correct. I have a large soft (and fluffy) spot for these flies; they have the most fascinating ecology being parasites of bees, wasps etc; they are some of the earlier flying flies of the season; and they are, I think, some of the most attractive little creatures. They are often very hairy and fly low down to the ground and they are out now!!! There have been sightings near here and I can’t wait to see one. But hurry as they are early season fliers. However, they like warm and sunny days which are a tad sparse at the moment!!!!


Within the UK there are not many species but here are the ones that you can find (although some of them are very rare!). I will break them down into their subfamilies and attach photos so you can see the differences. The photos are taken of our specimens in the British collection at the Museum.



BOMBYLIUS Linnaeus, 1758

canescens Mikan, 1796 +

discolor Mikan, 1796

major Linnaeus, 1758 +

minor Linnaeus, 1758


The BOMBYLIIDAE include the species that are the more well known species, including the commonest UK ones. There are four in the UK;


Bombylius canescens Mikan, 1796 – These are found in southern Wales and South-West England and are generally scarce across their range. There was one recorded from London but, as with many of these cases, lots of the records need to be verified ... and more importantly more need to be made! 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 using their legs! Wouldn’t that be an amazing sight!


Bombylius canescens.jpg

Bombylius discolor Mikan, 1796 - A smallish bee fly that has beautifully mottled wings. These are generally found in the Southern part of England but are fairly rare nowadays and are a UK BAP species. They parasitise the larger solitary bees (there are many records from the genus Andrena), which are active in the spring. As with much of our understanding about the ecology of all flies, much has to be determined as the exact hosts have yet to all be identified.


Bombylius discolor 1.jpg
Bombylius major Linnaeus, 1758  - This is the most common species and one of the early rises in terms appearing in the spring. One of the fun things about Bee flies is that when at rest their wings are fairly distinguishable from each other but in flight, these become a blur and so identification becomes harder


Bombylius major.jpg

Bombylius minor Linnaeus, 1758 – this is another one of the UK BAP species, commonly called the heath bee fly and is found on, heaths…..


Bombylius minor.jpg



THYRIDANTHRAX Osten Sacken, 1886

fenestratus (Fallén, 1814 - Anthrax)

VILLA Lioy, 1864

cingulata (Meigen, 1804 - Anthrax)

modesta (Meigen, 1820 - Anthrax) +

venusta (Meigen, 1820 - Anthrax)


There are again 4 species represented in Britain from the subfamily EXOPROSOPINAE and they differ considerably from the previous by all being short tongued species. We once had an enquiry at the Msueum describing a very small fluffy flying narwhal … we knew what they meant though!


Thyridanthrax fenestratus (Fallén, 1814) - this is a very distinctive species with blotch patterned wings. Alan Stubbs describes them wonderfully in his book on solider flies and their allies as having ‘extensive bold wing markings with some tiny clear windows!’ - I can picture them exactly.


Thyridanthrax fenestratus.jpg


The next three are from the genus Villa, which at genus level are fairly easy to recognise with their clear wings and their rather flattened blunt abdomens (this again is taken from Alan Stubbs brilliant book on British Soldier flies and their allies – he has such a lovely use of language!!). However species level identification is a tad trickier. The keys worry about scales on their abdomen, which inevitably rub off! And there are subtle changes in morphology from the norm which is not helpful – the insects play with us!!!


Villa cingulata (Meigen, 1804)   - a very rare species but this may be an artefact of poor sampling or people not turning in records. One place that is meant to be good to see them is the Warburg Reserve, just outside Henley


Villa modesta (Meigen, 1820) - The most widely distributed of the UK Villa species, mostly on sand dunes in England, Wales, Scotland and has been recorded in South-East Ireland.


Villa modesta.jpg

Villa venusta (Meigen, 1820)



Now this is a rare species, associated with Lowland heaths (it is an RDB2 species). There have been records from Dorset, Devon and Surrey but not for a long time.  However, we have no specimens in the British collection at all! They are found in mainland Europe and we have some from there but it would be really interesting to see if any are around. This in the past have been collected later in the season (mid-July to late august) which should tie in lovely with peoples summer holidays!!




PHTHIRIA Meigen, 1803

pulicaria (Mikan, 1796 - Bombylius) +


Phthiria pulicaria (Mikan, 1796) 


This tiny bee fly is recorded widely on sandy coastal areas of Britain. It is locally abundant on many sand dunes with some 25 known post 1960 sites. As with the other bee flies the larvae are parasitoids, with hosts including caterpillars of a micro-moth (Gelechiidae), but with greater time studying their biology it is assumed that many more hosts will be discovered (Stubbs & Drake 2001). Adults are seen from June to August and characteristically visit the flowers of various low hawkweed-type composites but they can often be overlooked as they are tiny!


Phthiria pulicaris.jpg

(isn't it a cutey!!!)


And Systoechus ctenopterus, the new one confirmed by David Gibbs, all very exciting! It is the first new bee fly on the British list for a very long time.



It looks a lot like some of the other bee flies but the position of cross-vein r-m differs in this species in comparison to the more common Bombylius species. In Bombylius it is approximately in the middle of discal cell (d), well beyond m-cu but in Systoechus these two veins are opposite.


Below is a typical wing of the Bombylius with all of the veins labelled. I spend a lot of time looking at wings trying to decipher what vein is what. This can often be very frustrating!! Also the banded appearance of the abdomen is a good indicator of this genus. As David states, the other species are from Southern Europe and less likely to have such distinct banding. In the museum collection we only have this species in the main collection as we have never collected any from the UK previously.




So this is great on two counts; one- a new species to Britian of a very cute little fly and two- it was identified through iSpot. This is an online service aimed at helping people with faunal and floral identifications. They have a team of experts (of which David Gibbs is one) dotted round the country to aid with identifications. These are not the only online places though – the Museum also do this and I have had many a request on random maggots and strange looking flies


Just before I finish this piece there is one final group of bee flies that I wanted to mention and they are in the genus Anthrax! Now these were included on the British list on the basis of specimens with locality data in Leicestershire, but it is now considered to be wrongly recorded as British. There is nothing scary about this genus though which is entertaining as we still have problems sending specimens from the main collection to people on loan- I mean, would you like anthrax in the post?

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