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"A Nature Observer′s Scrapbook"

Flies - True, two winged flies of the order Diptera.

Page 3 - Tachinids, Blow flies, House flies and Warbles.

Eriothrix rufomaculata

Tachinid sp

Eriothrix rufomaculata

At first glance this species can easily be dismissed as 'just another black fly'. But, a second look will reveal the dull red patches on the sides of the abdomen, the smoky brown wings and a very bristly appearance.

This specimen was seen on garden potentilla but it also favours a wide range of wild flowers, ragwort, creeping thistle and hogweed, etc., from June to September.

Originally it was thought to be an immigrant species but, it is now confirmed as a breeding resident in the UK and it has been reported as far north as Inverness-shire. In mainland Europe it breeds by parasitizing the caterpillars of certain Tiger moths. But, in the UK there is evidence of it parasitising the larvae of Chrysoteuchia culmella, a very common Grass Veneer moth (this link to refers).

09.09.2005 On Potentilla in back garden.

Mintho rufiventris

Tachinid sp.

Mintho rufiventris

I don't usually photograph every fly that I see but, this one 'looked a bit different', it was nicely presented against a white painted wall - and, most importantly, calmly posed for the camera.

I recognised it as a Tachinid but, when I had it identified it turned out to be something of a surprise. Previous records of the species had apparently been confined to South East England south of the Wash. So, its appearance in Lincolnshire would appear to be an example of the northern drift of species due to 'global warming'.

It is more common in continental Europe. It's flight period in the UK appears to be from May to early September.

The larvae parasitise caterpillars of the moth Orthopygia glaucinalis which live in decaying plant material such as hay stacks and thatch. We have the hay but I have never seen the quite distinctive looking moth.

28.08.2006 Found posing, mid-day on the garage wall.

Gymnochaeta viridis

Tachinid Greenbottle

Gymnochaeta viridis

This is one of the more easily recognisable Greenbottles. That it has a very bristly abdomen and a distinctive wing venation identifies it as one of the Tachinid family - and the fact that there are not many green-bottles flying in early Spring narrows the choice down considerably.

Whereas many other greenbottles are associated with dung or decaying plant and animal material, the female G. viridis lays eggs on the stems and leaves of plants and trusts that, on hatching, the minute grubs will find moth caterpillars that they can parasitise. That might seem a big enough challenge in itself but, they specifically favour Black Arches and Small Dotted Buff moths which must stack the odds against their survival even farther.

05.04.2009 Sunning itself on an exposed white painted wall.


a Flesh-fly

Sarcophaga species

Within the 'Blow-fly' group, there are several Sarcophaga species that are very difficult to positively identify without very close examination. So, placing a species name against a photograph is somewhat meaningless. They come in large, up to 15mm, and small sizes and not even their striped thorax and chequerboard abdomen is specific to this genus.

After mating, the viviparous females allow the fertilised eggs to develop within their bodies and produce live larvae, which as their common name suggests, they lay in carrion.

They may be found all year round.

10.05.2004 Found on nettles.

Bluebottle Bluebottle

a Bluebottle

Calliphora species

It is very difficult to positively identify individual Calliphora sp. Bluebottles.

Like all Blow-flies, Bluebottles frequent excrement, carrion and other decaying material. Not the most endearing insects.

The female Bluebottle is capable of laying as many as 600 eggs. These are laid on the favoured, fresh food source and hatch very quickly before it dries out, so that the larvae can burrow into the parts likely to remain moist.

At up to 13mm long Calliphora sp. are substantial flies and are very common, worldwide.

19.05.2004Back garden, near the cess-pit!
30.09.2004Sheltering from rain on outside of window.



Neomyia cornicina
previously known as Orthellia cornicina

There are several look-alike Greenbottle species. They occur in different fly families and to the inexpert eye can look confusingly similar. Positive identification from photographs is often not possible but, expert opinion suggests that this one is 'likely' to be Neomyia cornicina, from the Muscidae family.

Whereas some greenbottles choose to breed in such places as dead carcases and even on open wounds of larger animals, this Neomyia species breeds in dung.

The flies are on the wing from April to October and are often seen on a wide range of flowering plants seeking nectar. This one was feeding on aphid 'honey dew' on the leaves of Salix caprea. The body coloration tends to bronze with age.

02.05.2005 On Salix caprea

Cluster fly

a Cluster-fly

Pollenia species

Identification of individual Pollenia species, even under the microscope, can tax the experts. But the genera as a whole can usually be recognised by golden hairs on the thorax. They are often seen with wings tightly folded back over the abdomen - even more so than the image suggests, resulting in quite a compact appearance.

Interestingly, their larvae parasitize earthworms.

They get their common name from their habit of congregating in large groups, 'clusters', in sheds, outhouses and lofts.

08.09.2005 Sunning itself on Salix caprea, completely un-phased by close attention of camera.

Mesembrina meridiana

Muscidae sp

Mesembrina meridiana

There may not be many flies that can be called handsome but, this one attracts my attention more than most. Unlike the Blue- and Green-bottles which are blowflies, this is a member of the Muscidae or House-fly family.

Apart from it's brightly polished thorax and striking orange wing roots, it also sports some rather fetching yellow footwear which highlight the three pads on each foot.

But, despite it's impecable dress sense, it still chooses to breed in dung and eat garbage.

Although it flies from March to October, I have found it easiest to photograph when it lazes around in the Autumn sunshine.

11.08.2005 Basking on Salix caprea.
27.09.2005 Basking on Iris by the pond.
02.10.2005 Basking on Salix caprea.
11.10.2007 30+ basking in sun on fence posts.
29.04.2009 First sighting of 2009.

Phaonia viarum

Muscidae family

Phaonia viarum

This is a fly which, at 10mm long, could be confused with a small Flesh-fly.

Maybe because of its smaller size, it seems to me to be much more nervous than Sarcophaga carnaria and I found it more difficult to photograph.

It flies from April to November and breeds in leaf litter.

11.08.2005 On Salix caprea.

Yellow Dung Fly Yellow Dung Fly

Yellow Dung Fly

Scathophaga stercoraria

Found from early Spring to late Autumn, a very well known fly, but positive identification is difficult because there are several similar species.

It is frequently found around dung, whether it be horse, cow or sheep dung, which gives it the unsavoury reputation of being a 'dung feeder'. However, it is the larvae which feed on the dung and the adult is actually carnivorous, feeding on the small insects which are attracted to the dung.

The upper image shows it with its prey. And the lower image shows it in its typical predatory stance, balanced on four legs with the forelegs tucked up ready to pounce on the next meal.

02.06.2004Common - especially around sheep droppings!

Sheep Nostril fly

Sheep Nostril fly - a Warble

Oestrus ovis

Oh, you'll love this.

The Sheep Nostril fly places already hatched larvae in the nostrils of sheep. The larvae move up the nasal pasages and lodge in the sinuses where they feed on mucus. When mature, they are ejected when the sheep sneezes. They then pupate below ground.

The larva shown was found alive at the bottom of a sheep water trough. It was 27mm long! and 8mm in diameter. (It is hardly surprising that the sheep sneezed!) The larva is normally white and the black banding indicates the first stage of pupation. While kept under observation the larva became progressively black and pupa-like.

The species is common in all sheep flocks.

07.06.2004Larva found in sheep water trough.

Lesser House Fly (?) Lesser House Fly (?)

Fungal infection of flies

Entomophthora muscae

This should put 'athletes foot' into perspective.

This fungal infection is known to infect many fly genera and since it causes distortion of the body and wings, attempts to identify individual affected insects is made even more difficult than usual. Never-the-less it is interesting to know what the condition is when it is observed.

The specific fungus involved is Entomophthora muscae (a zygomycete fungus). It attacks the internal body parts of the fly and only in its final spore release stages do 'sporangia' grow through the inter-abdominal segment soft tissues to give it a soft woolly external appearance.

At this time, the fly will have climbed to an elevated position. (I presume that if the fungus interferes with the fly's oxygen intake through the breathing spiracles on its body it would be natural for the fly to seek an elevated position to maximise whatever airflow is available.) It is also invariably seen with its wings held out at an un-natural, elevated angle. (Again, I imagine that if the fungus causes an irritation, it would be an appropriate reaction for the fly to raise its wings away from any contact with the fungus.)
Co-incidentally, both these actions result in the fungus being able to disperse its spores more effectively.

One of the main distinguishing features of the Diptera (Fly) Order of insects is that they have only one pair of conventional wings. The second wing pair are represented by drumstick-like 'halteres'. At rest, these are covered by small flaps called 'squamae' and these can be seen raised, like the wings, in the second image.

fungus spore dispersal)

The third image, has captured another infected fly that had conveniently climbed up a window pane prior to the explosive release of the fungus spores from the white sporangia. (The image shows the spores adhering to the window so this is not clever high speed photography catching the moment of release!) This method of explosive release means that the fungus does not rely solely on wind dispersal of the spores but can maximise distribution even in still air conditions.

A very good description of the fungus is to be found here on
Tom Volk's Fungi pages .

16.06.2004Found on fresh young rose growth in back garden.
02.08.2004Second infected specimen found on Cock's Foot grass about 100m from the first.
01.10.2008Evidence of spore dispersal on an outside window.

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