Highlights of 2013

December's been a quiet month on the blogging front - a large beetle project is ongoing (status review of the UK Chrysomelidae) and then of course the whole festive-season-thing. However, there was a proper summer this year with an extended period of hot dry weather extending into a mild autumn, and this meant some fine invertebrate (and other) sightings after some truly awful, cool, wet summers. The most spectacular (for me as they were all personal firsts) were probably three Lepidoptera finds between July and September - two butterflies, a monarch (Danaus plexippus) and long-tailed blue (Lampides boeticus) and a moth, the Clifden nonpareil (Catocala fraxini). The monarch is a North American species, and although some have been known to cross the Atlantic, it is more likely that this (and one from a nearby friend's garden) had escaped from a butterfly farm, maybe on the Isle of Wight. Certainly there was a small flurry of records of this species in southern England, aided by the fact that monarchs in the UK often visit gardens to seek their foodplant, milkweed (Asclepias syriaca) which is of course also non-native. The other two are scarce migrants seen in higher-than-usual numbers due to the favourable conditions this year. Being native to NE Europe, the Clifden nonpareil is more often seen on the eastern coasts of Britain, but my sighting was in Hampshire, about 10km inland where one large and unmistakable adult was seen basking on warm brickwork near scrub including its foodplants - aspens and other poplars (Populus spp.). Also a rare migrant, the long-tailed blue can be found on various Fabaceae such as everlasting-peas (Lathyrus spp.) and brooms (Cytisus spp.) - as a Mediterranean resident, it's not often seen in this country. I'll stop there, but if you'd like an affordable and user-friendly guide to European butterflies, one of my favourites is Haahtela et al. (2011). More to come from me in 2014, but until then, here are some pics from 2013...

A flock/mob of jackdaws in spring, as seen from my study window.

Adult female smooth newt in our garden pond.

A leaf beetle larva and its defensive shield of faeces and shed skins.

And finally, just to prove that I do go out and do ecology in the field, here I am taking great created newt eDNA samples at Claylands Nature Reserve, Hampshire.

Reference

Haahtela, T., Saarinen, K., Ojalainen, P. & Aarnio, H. (2011). Butterflies of Britain and Europe: A Photographic Guide. A & C Black, London.

A tiny clue that looks like poo

Sometimes a seemingly innocuous observation can lead onto an interesting ecological story... A couple of days ago while collecting bramble and raspberry leaves for my stick-insects, I noticed a small black-and-white cocoon attached to the underside of one of the leaves.

Black-and-white cocoon, 6mm long

Although the occupant has clearly emerged as an adult, I wondered if the distinctive black-and-white cocoon might be identifiable, at least to family level or similar. A quick web search made it clear that this was the pupal cocoon of an ichneumon and it didn't take long to find out that the pattern (which maybe camouflage it as bird-dropping or piece of mould?) is characteristic of the genus Hyposoter (subfamily Camploplaginae).

At least 15 species of this genus can be found in the UK and they parasitise the caterpillars of various butterflies and moths such as the Lymantriidae (tussock-moths), Pieridae (butterflies - whites and yellows) and Lycaenidae (butterflies - coppers, hairstreaks and blues). They do so by the female wasp laying an egg in the host caterpillar, piercing it with her ovipositor. Once hatched, the wasp larva develops inside its host which shrinks, becoming a hard,  brittle shell - effectively mummified. When ready to pupate, the wasp larva spins a cocoon inside the larval skin (or in some cases the host skin splits and the wasp pupates outside) and this creates the black-and-white patchwork pattern - it takes about a month from the egg being laid to a new adult emerging.

I don't know which Hyposoter this is and I doubt that it's possible to tell from just a cocoon. However, one of the British species (H. ebeninus) has been filmed going through its life cycle, and this is certainly a candidate for the species here as the adults match ichneumons I have seen but not identified (though that isn't a reliable indiactor - they are a diverse and tricky group to ID), and parasitises the cabbage white butterfly (Pieris brassicae) which is common here. Again, this is not enough for an identification, but it is something I can look out for next season. In any case, I hope that's an interesting little ecological tale from a passing observation.

Close-up of the Hyposoter cocoon showing silk threads attached to the host's mummified skin.

The spider with emerald jaws

As well as mystery cocoons, breaking up some old fence panels for firewood dislodged numerous scuttling invertebrates. Plenty of woodlice, barklice and so on, and many small spiders, but also a splendid specimen of Segestria florentina. This is the largest species of the familt Segestriidae in Europe, with females reaching up to 22mm in length (excluding legs and other appendages). The family is distinguished by having 6 eyes arranged in a semi-circle (most spiders have 8) and the first three pairs of legs directed forwards (most have the first two forwards and the other two backwards). Although this species can bite (it's apparently painful, a bit like a bee sting or sharp jab with a pin, but not dangerous to humans), when disturbed, they curl up or flee to find a crevice to hide in - being nocturnal hunters using tunnel-webs with radiating threads. First found in Britain in the 19th century, this is a circum-Mediterranean/continental species that most likely arrived with ships to ports in southern England and has since spread slowly northwards - a likely candidate to increase its range as mean temperatures rise with climate change.

A large female Segestria florentina, characteristically curled up when disturbed during daylight.

This photo shows the first three pairs of legs pointing forwards very clearly. They are generally a fairly uniform black in colour with some faint paler marks such as the median line seen here, although this has been enhanced by the camera flash - to the eye, this was a very dark spider. However, the chelicerae (jaws, bearing the fangs) are an iridescent green. She needed a little gentle persuasion to show these, then was allowed to scuttle away under the shed - we do after all run a spider-friendly household...

The iridescent green chelicerae of S. florentina - the arrangement of eyes is also just about visible. Note that I am not testing her ability to bite.

Multiple cocoon of many mysteries

I'm not often stuck for an identification, at least not for long but while dismantling an old fence panel a few days ago, I did find some things I really couldn't identify, at least maybe not...

Cocoons found attached to an old fence panel

The left-hand one is in some ways the easiest - it's probably a moth, maybe the knot grass (Acronicta rumicis) which I have seen in our garden and which makes long grass-covered cocoons (this one is around 55-60mm long including the grass) - hopefully I'll find out for sure when it emerges as it's now in one of my hatcheries.

The other one is less straightforward. As there's a cigar-shaped cocoon inside it, it is more of a nest than a cocoon as such, and appears to have two concentric 'walls', the inner one thicker and covered in tiny wood fragments.

The 'inner' nest around 18mm long, the cocoon inside is around 8mm long.

The cocoon within the inner nest - whatever was inside has clearly emerged, leaving an open end with a small 'lid'

Next to the cocoon, there's clearly a small black shape, plus in the very top photo, there's material between the two nest walls.

The small black shape turns out to be a dead and shrivelled caterpillar - whatever it was, it bore long hairs/bristles which can still be seen. Length approx. 6mm

From this angle, the true legs can be seen towards the head end (left) curled under the thorax, while the larger, stubby prolegs are more clearly visible in the middle/rear

The relatively simple lens/eye arrangment of the caterpillar

I can't tell what this caterpillar is as it is dry and shrivelled, but the form of the inner nest suggests a puss moth (Cerura vinula) or other member of the family Notodontidae. Mature puss moth larvae are large and spectacular, but the first instar is small and black. However, it doesn't have long bristles, so can't be this species, though other members of the family may be plausible candidates. A different question does arise though - cocoons give rise to adults, not larvae, so what is it doing here? If there were wasp eggs, then one plausible explanation would be that it was brought in immobilised by a solitary wasp as a food source for its own young. However, this is a nest with a cocoon in it, not eggs. Also, there is no evidence of a wasp in the cocoon, but there is the material between the inner and outer nest walls. I am unaware of any wasps where a host caterpillar is entombed by a pupating larva to await its adult emergence, but they are a diverse group  often with complex (and often poorly understood) life-cycles, so I imagine it is possible. Alternatively, the caterpillar was simply caught inside a nest construction and starved.

Spider exuviae (moulted skins) within the outer nest

As seen in the photo above, the material consists mainly of moulted spider skins (exuviae) of differing sizes, sugessting an individual spider grew and moulted several times using the thin outer nest (the red structure top-left is a set of mouthparts, almost as large as the whole skin bottom-right). It seems plausible that the hiding place was a good one and a spider simply used it, building its nest around the tougher one already there. Looking even closer there is more to see.

The thin outer wall and the thck inner wall with wood shavings. Just below where they meet, a small white structure is visible in partial shadow.

Hidden behind the larger structures, what appears to be another, much smaller cocoon. This is now also in a hatchery awaiting whatever emerges.

This looks like an opportunistic cocoon-builder that has just used a handy crevice, but it may be related to the larger nests. I don't know which species are involved, but I hope that the two remaining cocoons remain viable and I'll see which species emerge. You never know, it might shed some light on the mystery nest/larva - and if it does, I will, as ever, post it here.

The widow and the vapourer

While collecting brambles to feed my ever-hungry stick-insects, I noticed a batch of insect eggs on top of a silk mat and tunnel which had knitted two of the leaves together. Of course I had to have a closer look and the eggs were of the vapourer moth Orgyia antiqua, while the tunnel contained a spider which I think is probably one of the Steatoda 'false widows' which are mostly harmless but recently seen in many a tabloid frenzy about deadly spiders - I could probably ID it to species but not without pulling it out of its retreat and I'd rather leave it be as I suspect it found the ready-made moth cocoon to be a handy basis for a web (or maybe it happened the other way around). However the moth eggs do lead onto some interesting biology/ecology.

Vapourer eggs on the female moth's cocoon, under which a spider web/tunnel has been created

Entrance to the spider's retreat - I wonder if the black hairs round the entrance are from a vapourer caterpillar or something else. The flask-shaped moth eggs are clearly visible, including the dark dimple and band at the top.

The spider, probably Steatoda sp. is just visible within

Female vapourers are wingless and do not disperse as adults. Instead when they emerge from their pupal cocoon, they emit pheromones to attract the winged males (they are highly active flying zig-zag routes during the day, and sometimes at night, to find females) and once mated lay their eggs on their old cocoon. The larvae, which feed on various trees and shrubs, are highly distinctive with tufts of yellowish hairs on their dorsal surface and longer, narrower tufts at both ends. The adults are less spectacular and images of them can be seen on the excellent UKMoths site here.

Vapourer moth larva

Vapourer moth larva

Vapourer moth larva

No clouds, no rain, no cold, November

This title of this post may well be inaccurate by tomorrow, but for now - in this part of Britain at least - it is warm, dry and sunny. More importantly, it has remained warm apart from a couple of cold nights and dry apart from a few days of stormy rain for much of the autumn. This of course affects our wildlife. For example, a 'proper' hot, dry summer after several cool, wet ones has seen butterfly populations bounce back to some extent, and this is likely to be helped by a long warm autumn. Undoubtedly, migratory birds will have done better than in previous years, being able to find more food for there long autumn flight, and hibernating species will have a better chance of storing enough energy for the winter. Personal observations also bear this out - garden birds are not using our feeders so much as they have been (though I have seen plenty of birds around) - presumably there is still plenty of wild food available.

This year our strawberry plants have fruited into November - some wild plants will be doing the same

A long season of favourable conditions means that breeding/reproduction can go on for longer with 'extra' broods possibly being squeezed in before winter. I have seen late jackdaw broods in chimney-pots nearby, but on a smaller scale, the female Steatoda nobilis false widow spider (one of the species associated with tabloids' recent scaremongering) that lives in our garden storage box has another brood which she guards closely.

Female Steatoda nobilis guarding her egg-sac - two old sacs remain showing that this is the third brood in this sheltered location.

 Of course, it is autumn - leaves are turning yellow and falling - and it has been damp recently, so Fungi are also appearing to remind us that this is not simply an extension of summer. There are 'toadstool' or mushroom-types of Fungi, but personally I am drawn to the smaller species (as I am with invertebrates), some of which have appeared, almost overnight, on some of our garden woodwork...

 

The common species Coral Spot Nectria cinnabarina - associated with dead wood, here it is on a batten forming part of a garden shed

A small species on hardwood garden shelving - I haven't yet identified it but it look a little like an oysterling (Crepidotus sp.)

So, just a few observations about this autumn, but they do give a flavour of how the current and recent conditions affect the wildlife we see - hope you enjoy whatever you are watching out for!

The (not really) attack of the (not actually) killer spiders!

Over the last few weeks, there has been a flurry of lurid headlines about 'killer spiders' and bites leading to horrible consequences, for example this one which was actually due to a streptococcal infection rather than spider venom - and of course infections can get into any skin puncture, but the tabloid fervour doesn't bother to mention this. In reality the spiders are the false widow Steatoda nobilis which bites few people - the species is not aggressive and there are no confirmed reports of anyone being hospitalised due to the venom. There can be bite symptoms such as chest pains and tingling in the fingers but nothing like the horror-stories in some sections of the media. Sadly, the media frenzy has led to people squashing them on sight and even closing a school where they were found - a major over-reaction in my opinion due to ill-informed health & safety officials being influenced by stories of poisoning and 'infestations'. Yes, it may be Britain's most venomous spider, but there really isn't much competition for that accolade - we have nothing like the Sydney funnel-web here. As it happens, I have one living in my garden storage box, and she's really quite pretty and although she tends her spiderlings carefully is quite timid and curls up behind her web if I point the camera too close. She does not leap at me, fangs clashing and venom dripping. Then again, a headline like 'mostly harmless spider occasionally causes minor irritation' wouldn't sell many papers...

Steatoda nobilis with spiderlings in our garden storage box

Fortunately there are more reasoned sources of information such as the Natural History Museum who get a lot of calls about this spider, and some rather better reporting about why they aren't anything to be scared of after all such as here and here. Yes, they are spreading (probably due to climate change) but have been in Britain since the 19th century and have been expanding their range significantly for 15-20 years - the 'outbreak' over the last few weeks is clearly more to do with awareness with more people noticing them (and panicking) following the 'killer spider' headlines. Still, it was interesting to get an unexpected call from the Guardian yesterday wanting to interview me about the spider - I was happy to do so, and the resulting article is here. The invertebrate conservation charity Buglife has an excellent page about spider bites, including advice about what to do in the unlikely event you are bitten and develop symptoms. So, happy spidering, please don't squash them, or have nightmares about them - they'll eat plenty of your garden and household pests if you let them.

The ladybird and the cocoon of doom

About 10 days ago, while cleaning one of my stick-insect cages, I noticed an adult 7-spot ladybird Coccinella 7-punctata with a silky cocoon stuck between its legs. Ladybirds don't make cocoons like that - what could it be? Some small invertebrates can be truly difficult to identify, but this one was, for once, straightforward as it is a common parasite of several ladybird species, Perilitus coccinellae, a wasp in the family Braconidae. But, to be sure I put the cocoon in a hatchery and waited...

Perilitus coccinellae cocoon, approx 6mm long

An adult P. coccinellae (a female - males are unknown) did indeed emerge and provides a good opportunity to look at a common, but often overlooked parasite.

 

Adult P. coccinellae - note the wing venation and the needle-like ovipositor with the abdomen curled under the body

Adult P. coccinellae - a closer look at the ovipositor

Adult P. coccinellae - see how the abdomen is curled under the body

The wasp has an interesting life history (as parasites often do). Although ladybird pupae are sometimes targeted, adults are usually parasitised. The wasp taps the ladybird with her antennae then curls the ovipositor forward and begins to tap and probe for weak points, laying a single egg into the ladybird along with trophic ('nutritional') cells which absorb food from the host so the wasp larva can feed on them once it hatches. It does not feed on the ladybird directly, although the diversion of nutrients to the parasite ipacts on the host's reproductive development and fat storage. After reaching its 4th instar, the larva chews its way out from the underside of the ladybird's abdomen, having immobilised it, possibly by affecting the host's motor neurones. It then forms the cocoon which is attached to the ladybird's legs. The ladybird is alive at this point which means that the wasp is protected by its warning colouration and reflex bleeding defence. The wasp then pupates, emerges as an adult and seeks a new host as soon as its wings are dry. The ladybird usually dies within about a week, either of starvation or fungal disease. Some host ladybirds do regain the use of their limbs although most are greatly weakened and die soon after. In winter the cycle stops for a while as the wasp larva hibernates within a host ladybird.

So, a bad end for the ladybird, but an interesting tale - if you'd like to read it in more detail, try Majerus (1994) which contains plenty more interesting ladybird info.

Reference

Majerus, M.E.N. (1994). Ladybirds. HarperCollins, London. [New Naturalist series]

The first fog of autumn

A non-technical post today - I'm mired in a swamp of academic marking, so something soothing is required... fortunately I woke up to a foggy morning which highlighted just how busy the spiders in our garden have been - enjoy!

A fine orb-web made by the garden orb spider Araneus diadematus

A large female garden orb spider Araneus diadematus at the hub of her web

A web shaped as a platform suspended from twigs and leaves - it reminds me of a mountaineering tent attached to cliff with pitons. Possibly made by a Theridion species, and there may be webs of spiders such as Linyphia tangled into it.

An incautious wasp becomes a meal for Araneus diadematus

Focusing on the familiar VI: ladybirds part 4

It's a year and a half since I started my occasional series looking in a little more detail at familiar species. In that post I looked at the 'typical' 7-spot ladybird Coccinella 7-punctata, including the yellow colour it shows when newly emerged as an adult, and compared it with the Harlequin ladybird Harmonia axyridis. This time, I decided to go back to the 7-spot and look in a little more detail at its external anatomy.

Dorsal surface of the 7-spot ladybird Coccinella 7-punctata

The dorsal surface is fairly straightforward and is what we usually see - the pair of wing cases (elytra) showing the familiar orange-red colour with seven black spot, the black and white pronotum in front of this, covering the thorax, and the head which is mostly hidden, although you can see the antennae protruding here. The ventral surface is a little more complex, and it's useful to become familiar with the standard terminology.

Ventral surface of the 7-spot ladybird Coccinella 7-punctata

I have ignored the appendages (legs, antennae and mouthparts) on this occasion but have numbered some of the other features that may be less familiar as they illustrate how the plates fit together to for the exoskeleton:

1. Epipleuron - the folded-under edge of the elyton which fits against the body.
2. Prosternum - the front section of the thorax (analagous to the sternum or breastbone in humans), which has a small keel running front to back (here a greyish line).
3. Mesosternum - the middle section of the thorax.
4. Metasternum - the rear section of the thorax.
5. The front section of the abdomen - you can see the curved join against the metasternum.
6. The 6th (and rearmost) abdominal segment. Ladybirds can be difficult to sex, but the shapes of these segments can be useful and there is more detail in Randall et al. (1992).

You will see the prefices pro-, meso- and meta- used elsewhere to mean 'front', 'middle' and 'rear' e.g. 'profemur' for the femur of the front leg. The plates have elastic membranes between them - the abdomen is particularly flexible in males as they need to curl it beneath in order to mate, and this affect the shape of the abdominal segments and membranes, leading to subtle differences that can be used to tell males and females apart.

That's all for now (maybe I'll write an intro to beetle appendages some time) - if you want to know more about ladybirds, especially from a UK perspective, have a look at the further reading list below, and why not get involved in the UK Ladybird Survey - new volunteers always welcome!


Reference

Randall, K., Majerus, M.E.N., & Forge, H. (1992). Characteristics for sex determination in British Ladybirds (Coleoptera: Coccinellidae). The Entomologist 111: 109–122.

Further reading

Brown, P., Roy, H., Comont, R. & Poland, R. (2012). Guide to the ladybird larvae of the British Isles. FSC, Preston Montford. A fold-out laminated sheet perfect for beginners.
Majerus, M.E.N. (1994). Ladybirds. HarperCollins, London. A classic - part of the New Naturalist series.
Majerus, M., Roy, H., Brown, P. & Ware, R. (2006). Guide to Ladybirds of the British Isles. FSC, Preston Montford. A fold-out laminated sheet perfect for beginners.

Roy, H., Brown, P.,  Comont, R.F., Poland, R. & Sloggett, J.J. (2013). Ladybirds (2nd ed.). Pelagic, Exeter. Much updated from the 1989 edition (which of course didn't have the Harlequin which wasn't in the UK then), an excellent little book with detailed keys to species, including the 'micro-ladybirds'.

Roy, H., Brown, P., Frost, R. & Poland, R. (2011). Ladybirds (Coccinellidae) of Britain and Ireland. FSC, Shrewsbury. Details of all species including maps, identification features, ecology and so on.

Dining on smut and other corny puns

A couple of weeks ago, I wrote about the smut fungus Ustilago maydis that grows on sweetcorn. While doing that, I found out that it is edible, and in Mexico is eaten as a delicacy called 'huitlacoche'. I also mentioned that if I found some more that wasn't quite so over-mature, I'd try it. I found some, I cooked it, and I ate it. So, in a rare departure from ecology on 'the spot', here are a couple of pics of the taste test.

A cob with U. maydis growing on it, being chopped and prepared.

Bits of huitlacoche fried and ready to eat.

The outcome of the taste test was pretty favourable - unsurprisingly a kind of cross between mushroom and sweetcorn, and quite subtle. I've found another growth in our sweetcorn patch, so that will be cultivated and I'll try more next time...

Grubs within grubs within grubs

Back in the 17th century, Jonathan Swift (he of Gulliver's Travels fame) wrote:

"So nat'ralists observe, a flea
Hath smaller fleas that on him prey;
And these have smaller fleas to bite 'em.
And so proceeds Ad infinitum."

Then, in the 19th century, mathematician Augustus De Morgan updated this to the more familiar

"Great fleas have little fleas upon their backs to bite 'em,
And little fleas have lesser fleas, and so ad infinitum."

Well, this might not proceed quite ad infinitum, but there certainly can be several tiers of parasitism. One common example involves the small wasp Apanteles glomeratus (family Braconidae) which parasitises larvae of the 'cabbage' white butterflies Pieris brassicae and P. rapae. Eggs are laid into the butterfly larvae, where they hatch and develop - after about 15 to 20 days the wasp larvae emerge and the host dies. The wasps then pupate in silken cocoons next to the dead host, creating the arrangement that can be seen attached to a wide range of substrates, sometimes in very exposed situations (such as the middle of a glass patio door...), with the whole cluster attached by silk threads.

A typical arrangement of Apanteles glomeratus cocoons by the dead host larva of Pieris brassicae.

Apanteles glomeratus cocoons showing the tangle of silk threads.

I have seen  numerous examples of this arrangement over recent days, largely because following several very poor summers in the UK, Pieris spp. are some of the few butterfly species to have done well, and consequently there are many of their larvae for parasites to target. Also, as Pieris spp. are ravenous eaters of brassicas in farms and gardens, A. glomeratus is a vegetable-grower's friend. However, if I look more closely, I might find 'hyperparasites' (parasites of parasites) such as the tiny ichneumon wasp Lysibia nana which targets braconids such as A. glomeratus. Closer still and - well, I don't think anyone has investigated - but I'd expect to find microscopic protozoan, fungal or nematode parasites. Maybe I need to capture some L. nana and have a look.

If you would like more technical detail about parasitic wasps, Ronquist (1999) gives details of their phylogeny, classification and evolution (including, in Table 1, some examples of who parasitises who). In contrast, if you fancy an excellent (and silly) photo of a braconid larva, try here instead (or, as well - I like both, and Myrmecos is a fine blog looking at entomology, often ants, from a more photographic viewpoint).

Reference

Ronquist, F. (1999). Phylogeny, classification and evolution of the Cynipoidea. Zoologica Scripta 28(1-2): 139-164.

Smutty farming

Yup, an obvious pun I know, but hey... as you may know if you read this blog regularly, I am a stakeholder in a community farm - we're chemical-free and pretty wildlife-friendly, and as such use either (a) cunning or (b) many pairs of hands to deal with pests. Of course, we get a few, but they can be interesting in their own right - like yesterday when I found a single fist-sized growth of common smut fungus (Ustilago maydis) at the base of one of our sweetcorn plants.

Common smut Ustilago maydis on sweetcorn

Close-up of U. maydis showing a small growth of the sweetcorn plant.

The fungus can grow on any part of the plant, though, as here, it most commonly affects the cob/seeds which expand and become filled with spores - essentially it causes a gall. It is fairly common, and its presence this year is unsurprising as conditions have been ideal - hot, dry weather while the plants are establishing, followed by rain as they mature - exactly what has occurred. It can cause major crop losses, though our non-intensive 'hands-on' approach means that we'll simply look out for and remove any more if they appear (the standard advice is to burn or bin them, but not compost them as the spores will survive and spread).

Interestingly though, I have found out that the fungus is actually edible, particularly if relatively young (this specimen was very mature and entirely spore-filled), and in Mexico is a delicacy known as 'huitlacoche' which is eaten in a succotash, or in tacos or omelettes. Apparently it's kind of nutty-mushroomy and quite nice but not popular elsewhere as it's seen as a 'disease'/'rot' rather than food - and I must admit it doesn't look that appealing. However, if I find another, less mature one, I'm going to try it - seems a good use of a failed cob! I may report the results here...

Syrphid detail

Sometimes I have to hunt for specimens, sometimes specimens come to me - in this case the hoverfly (family Syrphidae) Helophilus pendulus - a common species, often seen in our garden, in this case found recently dead on a windowsill. It could have been swept into the bin, but not before treating it as an opportunity to look at external hoverfly anatomy in the following series of annotated images.

Helophilus pendulus, dorsal view - note the strong, almost semi-circular, loop in wing-vein R4+5 (about a quarter of the way in from the wing-tip), characteristic of the hoverfly Tribe Eristalini. The pattern shows that the species (and genus) is a wasp-mimic. The fainter 'false vein' or vena spuria can be seen running much of the length of the wing (approximately in the middle) and is only found in hoverflies.

Helophilus pendulus, front view - the 'face' is clearly seen with its dark vertical stripe in the centre, running across two protrusions - (1) the 'knob' and (2) the 'lip' above a strong indentation.

Underside of the abdomen showing the hind legs most clearly - the hind tibia is at least half pale in H. pendulus as shown by the red bar.

The black-and-white pattern of the thorax is visible here as well as the fine bristles around the compound eyes (note the row of four relatively large dark bristled pores just behind the centre of the rear margin of the eye) and the ocelli (simple eyes) on the top of the head (red arrow).

Dorsal view. The red arrow indicates the semicircular protrusion ('scutellum') behind the thorax which covers (and presumably protects) the upper rear of the thorax and delicate membranes between that and the abdomen. The short bar top-left indicates the yellow 'gap' between the characteristic black abdominal markings and the rear of the segment.

As in all true flies (Diptera), the 2nd pair of wings is reduced to a small drumstick-like 'haltere' which has a counterbalancing/gyroscopic function beating the opposite way to the wings in flight.

The large posterior spiracle (red arrow) near the base of each wing - used for breathing along with the anterior spiracle found just above the base of each front leg, just behind the head.

One of the 'feet' - the 5th (of 5) tarsal segments is shown by the red bar - there are two claws (solid arrow), each curving past a gripping pad (broken arrow).

At the base of the wing there are various tufts of hairs which help cover the various joints between body plates etc and prevent material getting in which might cause damage or interfere with movement.

The front of the 'face' - the central vertical stripe ends at the 'lip' above a deep indentation.

The antennae are short and consist of three segments (numbered here) - the 3rd is expanded and bears a long sensory bristle called the 'arista'.

The lenses of the compound eye.

The extended mouthparts which form a three-segmented sucking/licking structure including sensory apparatus (e.g. for testing potential food), muscular pumps and so on. Liquid food is taken - dried nectar or pollen must be dissolved/suspended in saliva before it can be consumed.

There is of course more that could be covered here (and I may expand some parts with more detail in future posts), even without dissection, but if you want to know more, the following are books I regularly use:

• Rotheray, G.E. & Gilbert, F. (2011). The Natural History of Hoverflies. Forrest Text, Cardigan. Does what it says on the cover. More morphological detail/images would be useful, but still good coverage of natural history.
• Stubbs, A.E. & Falk, S.J. (2002). British Hoverflies. BENHS, Reading. Keys to adults of British species, many plates, including dissections of genitalia, detailed species accounts, and useful background information.

Enjoy!