34. Rhagionidae – naming

I knew this one would turn up in the garden eventually – Rhagio notatus, or the Large fleck-winged snipe fly. A beauty! But what’s in a name?

Rhagio – the genus was named by the Fabricius in 1775. According to the Mirriam-Webster dictionary, this is derived from the Greek ῥάγιον (rhagion), meaning spider, possibly because of their long legs, though I wouldn’t say the similarity was obvious. According to Harold Oldroyd’s 1969 Royal Entomological Society key to the family, Fabricius changed the genus name in 1805 to Leptis (possibly from the Greek λεπτός meaning “thin”) to avoid confusion with a genus of longhorn beetles called Rhagium. However, later authorities reverted the genus name of the flies to Rhagio, and the family name followed. The species name notatus comes from Meigen in 1820, a Latin word meaning “having been marked” – I am guessing that this refers to the strongly marked stigma of the wing, although there are nice markings on the abdomen too. Another species name, heyshami, was proposed by Curtis in 1838, presumably after the town Heysham in Lancashire, but Meigen got in first and so notatus it is.

Snipe fly – the only source I can find (Collins dictionary) says that this name arises because the flight of flies in this family is like that of the snipe. Now, is that the zig-zag flight of the bird when it is flushed, the characteristics of which allow you to distinguish snipe from jack snipe, or is it the eerie twilight plummeting of the male that makes its tail feathers thrum? That sound takes me back many years to the island of St Kilda when, to avoid the multiple snorers of the men’s dormitory and various nocturnal comings and goings, I took my sleeping bag halfway up Conachair above the village and slept out in my bivvie bag among the sheep fanks, falling asleep to the restless snipe’s headlong eerie throbbing. A painting, torn from its book, was given to me in honour of my eccentric nights out by Susannah, an art student who was camping out in the village, having somehow blagged her way onto the island. Village bay is at the top left and the circular stone walls of the fanks are in the centre, the perspective precipitous, like St Kilda itself. A scrawl on the back tells me to have a happy life, and which way up the drawing should go (though I think that was a joke), and two kisses, which would have been nice if delivered.

Another name reputedly associated with the family is “down-looker fly”, this being from the habit of the species R. scolopaceus perching vertically on trees and posts with its head facing downward. However, the fly I caught was enjoying the sunshine perfectly horizontally upon a redcurrant leaf, and Harold Oldroyd in his 1969 key doubts whether anyone uses that name. The same is probably true of “large fleck-winged snipe fly” which describes the fly but in a characterless way. I need to follow this one around and come up with something more fitting.

33. Piophilidae – persistence

This one took some effort. When I go out looking for flies there will be some that are distinctive enough that I know without the key what they are. Others I’m not sure about, or haven’t a clue, but are easy enough to key out. There always remain a few that are resistant to identifcation, and it has taken a lot of rainy days and effort for me to make a start on this stubborn backlog.

Today, I arrived, unenthusiastically at this one, caught in a trap baited with a mouse that the cat had helpfully brought home and not eaten too much of. I expected that this was going to be a hard one because the fly was small, shiny and black making it hard to spot the (black) bristles. Also, the way the legs are bunched up under the body is not ideal. But, faint heart never won fair fly as the saying goes, so yesterday evening I set to work and wasted a good hour going down the wrong part of the key having failed to spot an important bristle. Then, benefiting from another rainy day, I spent this afternoon trying to turn it into a sepsid since they have similar venation and are also small, black and shiny. But I couldn’t because it’s not one. Becoming more desperate, I tried alternative choices at several crucial points in the key, but I either ended up with nonsense or back at Sepsidae.

Eventually, I went back to the key in Coyler and Hammond’s Flies of the British Isles, and again came to Sepsidae. Having run out of ideas, I idly read the description of the next family in the book which happened to be Piophilidae, and everything suddenly fitted! Going backwards through the key I realised that I had lazily misread one crucial couplet, and that is what had led me astray. This is a family I have had been hoping to catch, mostly since their “common” name of “cheese-skippers” is interesting, as also the places to find them being given as enticed by cheese or bacon, on chicken legs outside a fox’s earth or on a dead fox on a gamekeeper’s gibbet. For the last month one of my home-made traps has been baited with Parmesan rinds, so far, to no effect.

from Rochefort et al., 2015, Canadian Journal of Arthropod Identification doi:10.3752/cjai.2015.27

I found a key to the “forensically important Piophilidae of the Nearctic” in the Canadian Journal of Arthropod Identification by Rochefort et al., (2015), copiously illustrated with visceral photographs of glistening fly corpses. Apparently piophilids are useful in working out the post-mortem interval, i.e. how long ago someone died, with the adult flies being most common in the “bloated and decay” stages. After a slight confusion resulting from their key leading me to couplet 9 which did not exist, I decided that the anepimeron was sparsely setulose (image 76 rather than 77) and that the fly was therefore Liopiophila varipes. The accompanying photo of the whole fly looked right and the distribution was described as being widespread, at least in Canada, the USA and Greenland.

Now scenting success, I found on the Dipterists Forum website that there was a key to the British Piophilidae by Alan Stubbs and Peter Chandler in a 1981 volume of Dipterists Digest. Although this was out of print, fortunately for me it was consequently available to download for free as a pdf. A quick romp through the couplets – quick because by now I knew all the bristles and twists and turns of the wing veins by heart – brought me again to Liopiophila varipes, described as “frequent”. According to NBN Atlas the species has a UK-wide distribution with the nearest records being from Fife in the early 2000’s on “long-dead rabbit”. Photos of the species on Diptera.info look just like it. Case closed, eventually.

Except that the next fly in the backlog, taken from the same mouse-baited trap has got a bristle on its shoulder where the first one didn’t, and so appears to be a different species of piophilid, Parapiophila vulgaris with slightly more British records, though none nearer than Northumberland. Is the first identification suspect with the bristle having broken off both shoulders, the scars being invisible against the shiny black body? How likely is it that two different species of the same obscure family happened to turn up in the same place at the same time? And did the cat actually catch the mouse or did it just happen to be passing by? Coincidence or evidence? My investigations continue …

32. Phoridae – backlog

Wherever I turn there are things needing to be done, and the Year of the Fly has just given me a another area in which to fall behind. Because it is spring I still have the illusion that the garden can be kept in order, a hope that a couple more weeks will sink with the lawn perpetually needing to be mown and the weeds stealthily overwhelming the vegetables. And because it is spring the bees are busy and thinking of swarming so I need to have supers and brood boxes prepared with frames and beeswax foundation ready for new colonies and honey, but they are sure to outpace me. And since it is spring, some spring cleaning should be undertaken, though detritus will no doubt accumulate in tidied areas as fast as I can clear them. And now that it is spring and the weather might at last be suitable there is ravaged paintwork on the windows that needs a paint … but instead I turn to the next fly in my backlog.

Since anything I catch that looks easy to identify gets preferential treatment, the backlog consists of small, dark flies that look like trouble. However, perhaps I am now beginning to get my fly eye in, for I looked down the microscope and thought “phorid”. The clues are the hunched back and the simple pattern of veins with the strong veins all crowded to the base of the leading edge, the other weaker veins more or less parallel and without cross vein. Clinching it are the strong bristles on the head and wings and the flattened hind femur whose concave surface can be seen glinting in the light.

From a previous bout of enthusiasm I have a key to the family in two volumes by R.H.L Disney, both written in the 1980s, one with a key to the genera (this fly is Megaselia I think, though dark hairs on a dark fly are hard to make out). The other volume has a key to the 200 odd species of Meagaselia, but of males only, and with the instruction that phorids should be preserved in alcohol rather than pinned. So since it is spring and the sun is shining and the leaves are green and the birds are singing and the flies are flying, I am content to leave it unidentified, for the moment, and instead go for a walk in the woods with the cats. There is a time for everything, and the time for scuttle flies is some way off!

31. Keroplatidae – bycatch

I am now in my sixth season of running a moth trap in the back garden, which to my great surprise has each year produced more than 100 species of moth in a startlingly diverse range of colours, shapes and sizes. The modern moth-fancier isn’t a heartless killer who impales everything on a pin to add to their collection. Instead they are environmentally-friendly gatherers of information who take only pictures before setting everything free again. Maybe it’s a bit inconvenient for the moth to spend a night in the trap, but the next night it can then get on with the rest of its life. At least, that’s the version wheeled out for the public.

The truth is that at some times of the year, the inside of the moth trap can look more like a Medieval depiction of Hell, with a mass of writhing bodies clambering over the corpses of those who have already succumbed, a tangle of legs and wings. Sometimes these are moths, especially if it rains and the inside of the trap gets wet. More usually though, the unintended victims are flies, thousands of midges and mosquitoes also attracted by the light, but burning up on the lamp or burning up their meagre store of energy in trying to escape from each others’ clutches. Few moth trappers will pay them much attention, myself included, merely tipping out their life-less, delicate bodies in order to keep the trap clean.

After going through the moths this morning, and liberating a lonely, restless cranefly, I stuck my head right into the trap, being a bit short-sighted, to see if there might be any interesting non-moths. Amongst the terrible harvest were some survivors, a couple of cecidomyiids and this enormously antennaed fly with long legs, a tiny abdomen and an unfamiliar wing shape and odd venation. The wings especially mark it out as being in the family Keroplatidae, previously lumped in with Myceotophilidae (fungus gnats), and the long antennae suggest that it is a member of the genus Macrocera (big horns). I was looking for one thing and caught another – long may it continue!

30. Tephritidae – Rorschach test

Psychologists know that a good way of getting people to talk about things that matters to them is to get them to talk about something else. What did you dream about last night? How did you feel about that? What associations does that image bring up? Or at another level of distraction, there is the ink-spot test where a meaningless blog (Freudian slip there – I meant blob) becomes a particular something that can be talked about as if it were meaningless.

Well have a look at this fly wing and tell me what you see. Relax – there is no right answer. Personally, I see Santa waving a greeting from his toy-laden sledge as a copiously maned lion pulls him across an icy lake while frenzied onlooking snow ghouls attack from every direction. Fascinating. Santa being Father Christmas of course, and the pull of lying (lion) might be man-ed? Go on. Well, this is the picturesque wing of Tephrita neesia, a member of the family Tephritidae, and a member of the superfamily Tephritoidea, commonly known, although I suspect by very few people. as picture-winged flies. Superfamily – interesting. How do you picture yourself in your family?

As the fly expert, obviously. It so happens that I have an unopened identification key to British Tephritidae on my shelves, Royal Entomological Society, 1988 by I.M. White. Just say that name again would you – I. M. White – I am right. Tephritidae – too afraid today. Would you say that you worry about, let’s say mistaking one fly family for another? Getting the identification wrong, so the book, the identity was unopened, unexplored…. Instead of the usual worries about the position of bristles on the face or how one wing vein meets another, the Tephritidae key is almost entirely based on the pattern of dark splodges, or by inverting the image, where the wing is clear or hyaline as it more obscurely terms it. You mentioned “inversion” and looking for bristles on a face – does either of these evoke a memory from your childhood perhaps?

The host for this fly is the ox eye daisy, which happens to be one of the flowers in the seed mix which I strewed upon what used to be the boys’ football pitch and is now the Meadow and where in late summer I can be glimpsed, topless wielding a scythe like the grim reaper himself. Wonderful! This is very interesting material indeed. Same time again next week – and just bring along whatever you catch – I think this blog of yours is going to be very fruitful material for us.

29. Cecidomyiidae – exotica

Suppose you were looking through a telescope and this is what you saw flitting through a tropical forest with shimmering wings and a noble pair of antennae held as proudly as the antlers of a 15-point stag. What imagined beast could be stranger than this unicorn-like fly, its diaphanous wings edged with a spider-silk fringe, its legs kinked as if to pounce, and a life history stranger than that of the phoenix? This is a gall midge with a body of only a couple of millimetres, and it would have developed inside a bump or thickening on its host plant that its own irritating presence had produced. I caught this one in birch woodland but since I can’t find a key to the 653 British species in the family, all I know about it is that our paths crossed.

One of my favourite books is Henry David Thoreau’s Walden which is, among other things, an invitation to pay attention to what is near at hand. He slyly wrote, “I have travelled a good deal in Concord; …”, making it clear that he was not writing a travel book, but an anti-travel book. He was interested in what is local and immediate, what is accessible to anyone who cares to look for it. Walden is full of inconsequential matters like who his neighbours were and what people shouted out to him as he was weeding his bean patch, of the woodchucks that ate his bean plants in the summer and his potato stores in the winter, though he grudged them neither and having tasted one, preferred to do without such meat. He writes of how he could tell when visitors had been to his cabin in his absence by bent twigs or flowers dropped some distance away, or a lingering pipe smell. A whole chapter on the characteristics and taste of the different ponds nearby, or on the animals living nearby or within his cabin; whatever the topic he draws from the particular to the general in his own quirky and humorous, but devastating way. And I like his finishing lines: “Only that day dawns to which we are awake. The sun is but the morning star.”

As part of my devotion to the Year of the Fly, I have been reading Life of the Fly by Thoreau’s longer-lived contemporary J. Henri Fabre. Here the intent is more obvious, but a similar approach; instead of expeditions to the tropics, Fabre studied the insects outside his backdoor, the behaviour of individual insects of a particular species and how they responded to his problematic interventions. He studied the putrefaction of blow flies and flesh flies on carrion brought to him by children for the reward of a penny, teasing them (the flies) with different kinds of barrier to see which ones they could circumvent and testing the maggots to see how far they would tunnel through soil to find a dark place to pupate.

Wordsworth celebrated the constraint of the sonnet in a sonnet that begins “Nuns fret not at their Convent’s narrow room” with the lines:

“Bees that soar for bloom,
High as the highest Peak of Furness-Fells,
Will murmur by the hour in Foxglove bells:”

For each of these writers, it is the self-imposed restriction of attention that provides their inspiration. Limitation is their gall, a tiny fragment of the world from which something unexpected and fantastic emerges.

28. Tachinidae – à la carte

Last year was the “Year of the Moth” in which a few select participants competed to see how many moth (and butterfly) species they could find with the equivalent of one hand tied behind their back. The rules were that we couldn’t use light, so no moth traps, lamps in windows or hanging about under streetlamps. Instead we reverted to more old-fashioned ways of finding moths such as dusk patrols, torchlight inspection of nectar sources and treacle/sugar/beer/banana/ rum/wines mixture painted onto trees and fence posts, competing with the birds to find caterpillars, digging for pupae, scanning plants for eggs and leaf mines, and daytime expeditions to promising areas, net in hand. Points were awarded for each stage of each species, so if you found an egg, larva, pupa and adult of something you would get four points. It kept us occupied all year, and between the four of us we saw signs of 273 species.

At the thematic dinner before the prize ceremony we had stripey caterpillar entrées, farfalle pasta (at least it was supposed to be, but the supermarket ran out and we had to make to with conchiglie or shell pasta in honour of the geometrid shell moths), some resonantly named wines, appropriate music (Madame Butterfly) and bespoke gingerbread biscuits. The prize was a naff piece of Spanish pottery decorated with a vaguely butterfly shaped blob of glaze.

One of the disappointments of last year (apart from my not winning the prize) was that one of the caterpillars that I had found, fed and carefully tended with fresh leaves, pupated not as a moth but as a tachinid fly. These flies are parasites of many kinds of insects, or rather parasitoids, since most of them kill their host as they eat them up from within. Last autumn a patch of mint in the garden was home to half a dozen or so jovial Tachina fera adults enjoying the last of the sunshine – it’s hard to imagine being a caterpillar with one of those developing inside you.

This year’s tachnid looked at first glance like a slightly smarter than usual greenbottle, a goldbottle perhaps. But a few things mark it out as being different. Like Tachina fera it is very bristly, and under the tip of its thorax is what looks like a silk pillow – an enlarged subscutellum which is characteristic of the family. Starting from a gallery posted by the Tachinid recording scheme (byline – its a bristle thing …) and working backwards through some rather tricky old keys (the terse Royal Entomological Society key to Tachnidae by F.I. van Emden 1954 and the quirkily constructed British Tachinid Flies by C.D. Day, 1948) I arrived at the conclusion that this was Gymnochaeta viridis. Hosts for this species are given as Small dotted buff, Black arches, Pale tussock, Common rustic and Shaded broad bar, an eclectic set of moths. Fussy eaters evidently.

27. Fanniidae – lost and found

16th May 2019

The day started off, as it seems to more often these days, with a hunt for a pair of missing spectacles. The degree of difficulty was much higher than usual however, as the search area was an acre or two of woodland with an understory of heather and bilberry and not much idea of where they might have fallen. There was the hope of finding green hairstreak butterflies, which would have been a notable first for me, but an easterly wind kept the temperature below their comfort zone and they didn’t appear. There weren’t even that many flies to distract me from the searching which was eventually brought to an unsatisfactory close.

Hoping for better things we decamped to the coast where there was strong sunshine but an even brisker wind off the sea. A wall brown butterfly patrolled the sunny side of a stone dyke and hogweed flowers attracted a few flies, some of which were missed, but two at least were empids. Heading down a steep track through a knee-high blockade of butterbur leaves brought us down to a quiet sandy cove. As we ate our lunch, perched on a table-sized grassy knoll, a kestrel was equally poised upon an even smaller patch of wind, fluting and flicking as the eddies tumbled against the cliff above, then dropping down hopefully, but fruitlessly before a twist of the wing took it away elsewhere. There were plenty of coleopids on the wrack, and I found an interesting looking acalypterate on a rock which I caught and put in a tube. But at some stage the tube lost its lid and so too the fly. Along the way I also had managed to lose half of my pooter, invisible now somewhere underneath the butterbur despite the second search of the day.

Returning home we climbed up through woodland and along the outside of the high wind-protecting perimeter wall of Seacliff House, now a Manderley-like roofless shell, just needing one of the ravens of the day to fly over and croak for complete gothic authenticity. I swiped at a dance of flies enjoying a beam of sunshine poking through the sycamore canopy and caught one, expecting it to be another muscid. However, two features of its wings mark it out as belonging to the sister family Fanniidae. First, the vein nearest the hind edge of the wing, just by the tip of the thorax, is sharply bowed so that it would meet the faint short vein before it were they both extended to the wing margin. Secondly, if you look at the cluster of three veins that flank the wing tip, the next one along the front of the wing is thicker, and the thinner one after meets the wing at the end of a straight run, rather than being kinked as for muscids.

The males of this family (which this one was, as you can see from its almost touching eyes) are notorious sun dancers, poetically described in Coyler and Hammond’s Flies of the British Isles as “indulging in sheltered spots under trees, and seem particularly fond of flying in and out of shafts of sunlight striking through the foliage; at one moment they are brilliantly illuminated, and the next, they have apparently vanished. I know the feeling.

26. Scatopsidae – terra incognita

I don’t mean to brag, but the Diptera families I have found so far this year have been relatively familiar from my preliminary youthful investigations. Some were bonus families due to taxonomic splitting where subfamilies have been promoted to families (Limoniidae, Anthomyiidae), and a few were putting a name to something that I at least knew by sight (Anispodidae, Dryomyzidae, Heleomyzidae, Sciomyzidae), but there weren’t any leaps into the unknown. But now I have taken the plunge.

Small flies are quite off-putting to identify, the taxonomic characters being harder to see, or possibly requiring me to acquire better optics and lighting. But for some reason I decided not to ignore this particular fly sitting on a post with its pals enjoying the first warm day in a week of unseasonably bitter Easterly winds. The warm weather had inspired an excursion to look for dancing moths, my entomological highlight from last year, a by-product of getting away from it all to avoid the omnipresent Royal wedding nonsense.

On top of a hill where the oak canopy happens to be conveniently at eye level, I came across first one and then a hundred delicate moths dancing in the sunshine. Their antennae were several times longer than their bodies and so slender that they bent in even a slight breeze like the bow of a mast in a tempest. Their bodies glistened with a metallic sheen as they settled each on their own oak leaf, near neighbours but not too close, a couple of antennae lengths apart. Then at some invisible sign they would all launch themselves into the air and bob up and down for a bit, glittering in the sunlight. It was a sight I had never seen before, perhaps something no-one had ever seen before, and I felt like an explorer of strange lands. But, of course, these moths (Adela reaumurella) and their dancing are well known. Even so, a year later, the pleasure persists of having chanced upon something so delicately beautiful.

It’s a bit of a stretch to say that the same euphoria applied to finding this microscopic fly, but it’s cut from the same cloth, as was meeting up with the dancing moths again. When I looked at this tiny fly under the microscope, the pattern of veins on its wings was unusual with a knife shape formed by the leading edge (costal vein) and the next vein (R4+5) with all the other veins almost invisible against the transparent membrane of the wing. Something about that pattern was familiar – and sure enough there it was as Figure 58, Scatopsidae, in my Oosterbroek key to Diptera families. There are 46 species in the UK, breeding in various kinds of rotting things with the adults visiting flowers, but I had never seen or heard of them. According to Coyler and Hammond’s Flies of the British Isles, one species (Anapausis soluta) has been recorded swarming in large numbers in the noonday sun on wooden fences and similar places”. There is nothing new under the sun, as it says in another old book.

25. Empididae – surprises

The best kind of walks are when you find what you weren’t expecting. Our initial target for the day was a dead pheasant on a road verge in Berwickshire, reportedly ripe with beetle larvae which were to be collected up for the National Museum of Scotland. There was also a dead hare nearby, more road kill, which yielded up some more beetles, but that was all of that kind of work we had stomach for. We set off up the slope above looking for entomological action, but there was nothing much about, the air not yet warm and the birch leaves only just out, the oak still lingering in the bud. Some microscopic flies were spotted, offered to me and rejected – one has one’s limits. Otherwise I caught a March fly, a small muscid in the hope that it might be something else, and a few others for future puzzling. Then, crossing a scree slope a cry alerted me to what I had almost stood on .. an adder, also making the best of the faint-hearted spring weather. I looked less for flies and more at the ground after that.

Next stop was a commercial conifer forest, barren territory itself, though a fringe of bilberry could have yielded green hairstreak butterflies if the sun came out, which it didn’t. A relic of birch and oak woodland on a steeper slope was more interesting, with a pretty day-flying moth (common heath, Ematurga atomaria) which took some effort to catch. Some greylag geese honked in the valley below, and far in the distance a cuckoo called, always a pleasure to hear if you aren’t a meadow pipit. There was little else about, a drab micro moth, a tiny hoverfly (Neoascia tenur), and despite some muscular use of the sweep net on heather, a complete failure to find the larvae of a micro moth that builds a tiny protective case that looks just like the leaves.

Heading for home, late as usual, there was little hope of finding anything much now, but I kept an eye on the fence posts between the plantation and a tightly cropped sheep field. Where there isn’t much else to land on, a fence post can provide a warm, sheltered spot for a beleaguered insect. A couple of flies looked interesting and were expertly potted, but the star was a sharply marked micro moth with perky antennae, Esperia sulphurella, giving a tropical flavour to a distinctly Scottish landscape. Then, for no good reason, we detoured into a ride in the plantation and flushed a barn owl from its roost or nest high up in one of the trees.

The final surprise for the day was the discovery that amongst the fence post flies was an Empididae – a very stylish fly with its oversized wings, eyes that cover almost the whole of the head, outstretched antennae and stilleto proboscis. These are predators that catch and suck dry even smaller flies. Some species wrap up their prey in silk and present it to their chosen female as a prelude to mating. Who says flies are boring!