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2 Posts tagged with the bee_flies tag
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Tangled up in blue…

Posted by Erica McAlister Jul 29, 2013

After all the talk (and film) about the bee-fly and its long proboscis, I thought you should see the actual insect with the longest proboscis in terms of body size - and of course it is a group of fabulous flies - but that goes without saying! So this week’s blog is all about tangle-veined flies, known as Nemestrinidae.

 

fly.jpg

Nemestrinus bombiformis - showing their lovely wings

 

What has sparked this blog piece was my finally looking through some recent material collected by a colleague Duncan, one of the other fly curators. He has recently returned from Morocco with loads of my flies - the chunky ones including bee-flies, robberflies and these tangle-veined flies. This reminded me about some that had been collected by another colleague in South Africa. So I went to find where I had stored them, and track down all the literature I would need to identify it. But along the way I became quite obsessive about this little family.

 

So what are these tangle-veined flies? There are about 300 species worldwide in 23 genera, although none, sadly, are found in the UK. There is still much confusion about this family and the subject is crying out for a major overview. These flies are most closely related to the hunchback flies also known as the spider-killing flies (Acroceridae); and as with the Bee-flies and the hunchback flies, the larvae of this family are also endoparasites.

 

The adults are generally medium-to-large flies, often with hairy bodies, but all with a complicated vein pattern on their wings.

 

nemestrinidae wing.jpg

 

They are often brightly coloured, but if you look through the collection you will see many covered in pollen, which gives an indication to what the adults are feeding on! Within the family, some species have atrophic mouthparts - that is, they are no longer there or they are non-functional but most have the characteristic tube-like proboscis, which is often very long.

 

In the collection at the Museum we have 149 species registered from 14 different genera. The Museum houses about half the number of described species of Nemestrinidae.

 

We are always trying to increase the collections and enable greater access to them. There is not much point to a collection that is hidden away, and we are gradually enabling more of our collections be digitised for online access, as well as tweeting and blogging about them informally.

 

Not much is really known about this family (a common theme across the whole of Diptera). We do have some fossils - the oldest recorded is from the Middle-Upper Jurassic Karabastau Formation (a geological formation in Kazakhstan; about 160 to 145 million years ago) but when it comes to the extant flies we still have huge gaps in knowledge.

 

We think all the species across the subfamilies have hypermetamorphosis larvae - that is, the larval stages go through distinctly different phases of their development. And all of the family parasitise other insects (as far as we know). The female is quite extraordinary, as she can lay several thousand eggs in her lifetime on plants and surfaces that are generally off the ground (a housefly only lays about 500).

 

After about 10 days, these will hatch into very mobile larvae. These will disperse readily, often helped by the wind, to seek out their hosts. They can survive for up to two weeks in this state seeking out their hosts. This is just as well as they have very active hosts - the larvae of subfamily Trichopsideinae are all parasitoids of grasshoppers; the Hirmoneurinae seek out scarab beetles; and with Atriadopsinae it’s bush crickets.

 

neorhynchocephalus larvae.jpgneorhynchocephalus emerging.jpg

(Images taken from US Department of Agriculture website)

 

Within our collection we have four subfamilies represented. There is still discussion about how many subfamilies there are and where the different genera should be placed but I will work on the basis of the following groupings for the moment.

 

      1. Atriadopsinae
        1. Atriadops
        2. Ceyloniola
        3. Nycterimorpha
        4. Nycterimyia
      2. Hirmoneurinae
        1. Hirmoneura
      3. Nemestrininae
        1. Moegistorhynchus
        2. Nemestrinus
        3. Prosoeca
        4. Stenobasipteron
        5. Stenopteromyia
        6. Trichophthalma
      4. Trichopsideinae
        1. Fallenia
        2. Neorhynchocephalus
        3. Trichopsidea

 

There are some nice features to tell these subfamilies apart. Being me I have to get genitalia into a blog post somewhere, and for a change it is the female genitalia that holds the key to their ID - or rather, it is her ovipositor (egg-laying tube). The subfamilies Hirmoneurinae and Nemestrininae have telescope-shaped ovipositors that have retractile segments like a pump-action egg-laying machine! The other two subfamilies have sabre-shaped ovipositors, which bare two very long and slender valvulae (a scientific term for Diptera lady bits) from which she shoots her eggs.

 

But there is a more obvious way the subfamilies can be split apart: by their mouthparts.

 

Medium proboscis.jpg

Hirmoneura anthracoides

 

They vary from rudimentary, reduced, short, medium and long - in some instances very long. In fact one species of Nemestrininae called Moegistrorhynchus longirostris has the longest mouthpart in relation to body size of any insect.

 

longirostris.jpg

When I came across these in the collection I actually squealed in excitement. They have such a long proboscis because of the flowers they feed on - plants with very long necks; mainly the orchids and the irises. They do not generally fly with them out in front of them but held underneath their body:

 

94123bfb176759057e8d7d00c84a23ef.jpgFrom http://www.ispot.org.za

 

In South Africa there are a lot of very long-tongued flies (as they are known). There are also horseflies that have evolved from blood sucking to nectar feeding, with the development a disproportionately long mouthpart. Philoliche longirostris (= "long mouth"... no point having different names if it the best descriptor!) is one such horsefly, and Dr Shelah Morati has a fab website with some amazing images of them.

 

The tangle-veined flies are also are adapted to feeding from long-necked plants.

 

long tubular flower - Lapeirousia oreogena by Judd Kirkel W.jpg

These irises seem to have 'landing strips' for flies

 

The irises in the photo above seem to have landing strips that help guide the fly in. Work conducted by Dennis Hansen when he was at the University of Kwazulu-Natal discovered that if you paint over these strips, the flies cannot find the nectaries at the base of the tube!

 

cae63e6fe8068a9b8c08bccbdf3176de.jpg

From http://www.ispot.org.za

 

And many people have studied these groups, as they are amazing examples of co-evolution with very good models correlating corolla (the petals of the flower) length and proboscis, including work by Dr Bruce Anderson at the University of Stellenbosch! Great stuff!

 

The collection of tangled-vein flies the museum has been static for a while but we are now collecting more in South Africa, and recent additions to the collection prompted me to recurate the specimens. The drawers were shallow (resulting in many of the pinned specimens being put in in a jaunty angle) and they were also on slates.

 

uncurated nemestrinid drawer.JPG

Old-style storage

 

So after a week or so of updating the database and checking out any changes in nomenclature I have transferred the little cuties into new trays with spanking new labels into new deeper drawers. Job done!

 

curated nemestrinid drawer.JPG

New-style storage

4

Bee flies

Posted by Erica McAlister Apr 12, 2011

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.

 

BOMBYLIIDAE

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

 

EXOPROSOPINAE

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!!

 

 

PHTHIRIINAE

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.

 

Systoechus-ctenopterus.jpg

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.

 

500px-Bombyliidae_wing_veins-1.svg_.png

 

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?



Erica McAlister

Erica McAlister

Member since: Sep 3, 2009

I'm Erica McAlister, Curator of Diptera in the Entomology Department. My role involves working in the collection (I have about 30000 species to look after and over a million specimens), sometimes in the lab, and thankfully sometimes in the field.

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