24. Tipulidae – lazy bones

Not every fly that I catch is easily identified, even just to family. Some are so small that I am struggling to see any detail on them, or their legs are bunched in towards the body so that bristles are hard to make out, or the wings have folded across each other so the venation is obscured. Or they are acalypterates. For one reason or another, I am beginning to accumulate a bit of a backlog – a guilty conscience of flies in their own humiliating box. I could sit down and spend a lot of time trying to put a name to some of them, but the likelihood is that I will get grumpy and they will remain unidentified. Who doesn’t find the quick and easy job more tempting than the prolonged, difficult one, the gentle path rather than the high risk clamber to the summit?

So when my wife told me there was an “interesting fly” (note “interesting” and “fly” and that she alerted me to it … progress indeed!) in the porch and then when I saw what it was, it immediately jumped the identification queue. A brownish daddy-long-legs of this size would be bound to be a member of the family Tipulidae; I consulted the key and quickly proved myself correct.

Getting it down to genus and species would not be quite so straightforward, even using a modern key and with my boyhood collection to refer to. Just look at the work I had put into those carefully kept craneflies, each nestled on a pair of cardboard triangles, the box with its neat columns produced with a black thread, the labels laboriously typed out (capitals and underlining for family, capitals only for subfamily, initial capital for genus and none for species), the numbered labels all cross-referenced to individual record cards. I must have put a lot of time into identifying them, especially since I was using the slightly tricky and not very lavishly illustrated key by R.L. Coe (1950), which I had photocopied from Pelham-Clinton’s copy.

I particularly remember the excitement of finding Tipula maxima (the two large craneflies with strongly patterned wings in the bottom left in the box), to my mind the poster-species of the family. I caught them by the stream that ran along the edge of the back garden of my childhood home – that was on the 3rd July 1981 and I identified the following day. I would have just graduated from University and have been treating myself to some fly time in my last summer of freedom before starting a PhD on the molecular biology of influenza virus. But today the sun is shining, and it seems a shame to sit indoors fussing over wing veins, thoracic stripes and the cross-sectional shape of the bottom half of the ovipositor. I have been leaving my fly collecting for another day for most of my life – one more can’t hurt.

23. Sciomyzidae – sonnet 116

I have to confess that my interest in flies buys me no spousal brownie points. This is despite her mother being an avid Dipterist, albeit with an unconventional, Dyson-sized pooter and a simplified, but functional taxonomy (“Dirty fly”). I probably didn’t brag about my entomological weakness when we were first becoming an item, distracting her successfully with lavish dinners and romantic holidays. Twenty something years on, becoming somewhat bolder, I have been introducing fly collecting as a normal household activity and flies as an unremarkable topic of dinnertime conversation. I have to report that so far I have found very few weaknesses in her general distaste for their insect charms.

One of the problems has been the bees at the bottom of the garden which were not always as gentle as they are now, and when my first clumsy beekeeping activities coincided with shrieks from elsewhere in the garden, I knew that my cause was set even further back. They don’t help by peppering the whites on the washing line with tell-tale yellow polka-dot droppings when they stream out of the hive on the first warm day of spring. More entomological rancour comes from the clothes moths (Endrosis sarcitrella, since you ask) which I am blamed for having introduced on two ragged dolls, mementos of my pre-marital travels in Peru. Even travel has insect-related difficulties since, however heroic my counter measures, each mosquito bite she receives blossoms into in angry red and itchy blotch.

However, not willing to give up, and knowing her love of cooking and a good feed, I wondered if the way to endear me and my six-legged friends to her might be through food. So since it is the Year of the Fly I cooked her the most delicious fly pie, replacing the usual apple leaf decorations with something much more interesting. Well, I thought it looked delicious ….

Maybe now I have the answer. Our gardening duties are split between us, with mowing, fruit and potatoes being my responsibility, while she does the vegetables. Every spring her greenhouse becomes home to hundreds of pampered seedlings. Then, as delicate adolescents they are allowed outside on sunny days to toughen up, but there is a strict evening curfew and they are back under their glass duvet before a sneaky frost can nip them. Eventually they come of age and are planted out in a carefully prepared, weed-free plot, fending for themselves with just a yoghurt pot slug collar for protection. Then the carnage begins. Leaf by leaf, plant by plant, a nightly toll is taken by slugs and snails streaming across the lawn from cracks in the walls, from hiding places under boards or piles of mulch. When a row of carrot infants disappears overnight, my attention is brought to mollusc-sheltering patches of long grass that have been missed by imperfect mowing.

The fly that will charm her is this perky fly with its eager antennae and business-like spotted wings. It’s a member of the family Sciomyzidae, whose larvae eat snails and slugs. This particular one was swept from the edge of a large pond, and its larvae only eat aquatic snails. But there must be others who could help protect her seedlings. I feel sure that, if I can find the right way to bring up the subject, this is the family that will bring about matrimonial harmony. Let me not to the marriage of true minds admit impediments …

22. Lonchopteridae – veinistry

Beetle – opaque
Butterfly – distracting
Wasp – complicated
Caddis – dull

One of the things that flies have going for them that other orders of insects can’t match is the their sublime wing venation. Beetles hide their flying wings away under opaque wing-cases, butterflies and moths cover their wings with distracting scales, dragonflies wings are crazy paving complicated, caddis fly wings are drab, wasps too confusing …. you get the picture. But apart from the pesky Psychodidae (moth flies), flies present a single pair of unadorned transparent membranes, sometimes helpfully spotted in distinctive ways, but never in such a way as to obscure the quirky, family specific and aesthetically pleasing patterns of veins.

I particularly like the wings of Lonchopteridae which are symmetrical in outline, curving off gently to a pointed tip, the shape of a petal or a leaf, a wing designed to look good rather than for fancy flying tricks. The veins are relatively simple, each pursuing a steady course from a busy base to find its own patch of wing margin. There are no cross veins to confuse the picture, and just one forked vein to fill in a gap. Most endearingly, in females the vein nearest the hind margin of the wing joins up with its neighbour but in the males the vein keeps its distance and finds a solitary way to the wing margin.

Now, the most common difference between male and female flies, excluding their genitalia, is that males flies often have larger eyes that fill every bit of the top and front of their heads. Many of these male flies form mating swarms or otherwise chase down females, so the male goggle eyes make evolutionary sense. But what advantage can the subtle change in wing flexibility produced by having slightly different venation make? Perhaps whether or not those two veins meet is just an unintended and inconsequential consequence of some other more important difference between the sexes. Might it also be true that in our species men are prone, for no apparent benefit, to snoring, baldness, pot bellies and a tendency to take obsessive interest in particular aspects of their environment. I am only admitting to one of those.

21. Bombyliidae – probability

19th April 2019

My reward for giving the lawn its first cut of the year, apart from having a tidy lawn, was to come across a bee fly feeding in the flower border. I rushed inside to get a camera, and when I got back it was still there, but as I tried to get close enough to get a picture it disappeared up to the roofline and away and never reappeared. If I had brought a net I might have had a chance of looking at it properly, rather than just seeing a brown, fat and furry body with a probing proboscis. Although its wings were always a blur, my impression was that they were darker at the front, which suggests the dark-bordered bee fly Bombylius major. Only four species in the genus are found in the UK, with the NBN maps below showing the records for, respectively, B. canescens, B. discolor, B. major and B. minor. The sparse Scottish records for B. canescens are all a hundred years old or more, so the distribution also fits B. major. Dare I submit the record to Bee-fly watch without a corroborating witness, a picture or a specimen, and with no possibility of using a proper identification key?

I do have a specimen of B. major in my collection with the label 27.4.80, Stanmer, Sussex, and the back of the label has the grid reference TQ348102 which means that I caught it on a Sunday just after the Easter holidays at a site a few hundred yards north of the Sussex University campus. This was probably on the path there that leads from there up towards the South Downs, and I suspect that this was the first bee fly I had ever seen since I would have certainly coveted one for my boyhood fly collection. The occasion was most likely a University Natural History Society field trip, since surely I wouldn’t otherwise have been on campus on a Sunday. I was the Secretary of the Society, or at least I was the one who wrote a newsletter each week, in my neatest writing, to be surreptitiously photocopied by a PhD student who had access to a departmental machine. The print run was fairly small and the feedback non-existent. Well that has all changed!

Now that I think of it, one of those newsletters may have featured my own drawing of this very fly, though I can’t seem to find a copy, so perhaps I have imagined it. At any rate, this is a marvellous fly, never to be forgotten by anyone who sees it in action, a hummingbird for northern latitudes and a sure sign that spring is, most probably, underway.

20. Syrphidae – super sleuth

I was up early enjoying the sun at breakfast, but someone was up before me with the same idea. For a couple of days I had been trying to get a picture of his sort or swipe at one of them with my net, but they were too fast for me, but now the tables were turned and I could see who he was without bothering him. Or rather, her – the eyes of the males meet above the antennae, whereas her eyes were separated by a shiny forehead. This is one of those hover flies that can be identified from by sight or from a photograph and is Eristalis pertinax, one of the first hoverflies to appear in the spring. Though I have never seen one, the larvae of flies in this genus (known as rat-tailed maggots) have a distinctive long breathing tube that allows them to live safely underwater without having to come up for air.

Which brings me to my greatest (and only) success as an investigative entomologist. As the Secretary of my local beekeepers’ association, I would often be called up about bees nesting under the garden shed (usually bumble bees) or the attic (usually wasps). After a few pertinent questions about hairiness, size and colouring I could work out which group was involved and dispense advice, usually along the lines of “If you can, leave them be and they will be gone in a few months”. However, one caller was insistent that it was honeybees that were getting into her bedroom, and could I come and have a look. There often isn’t much a beekeeper can do once bees have set up home in your house – it’s a case of put with them or kill them. However, I took pity on her and set off on my bike to investigate.

Statue of Sherlock Holmes in Edinburgh, Photo Siddharth Krish, Wikipedia

The scene of the crime turned out to be a top floor flat on the main street in town, and the bedroom had a low sloping ceiling that, from about waist height, sloped to follow the roof line. The honeybees, as you may have guessed, turned out to be Eristalis hoverflies, and it greatly reassured the damsel who had summoned me when I told her there was no risk of being stung. She tried to distract me with the offer of a cup of tea, but like Sherlock himself, I followed the clues wherever they might lead. The flies were only appearing in the bedroom of the flat, and I was assured that the flies would appear whether or not the window had been left open. Hence, they must be coming through the walls or floor, and there was no good reason for them doing this as adults whose only interest is in finding flowers and mates. But what if they had got into the walls or roof space as larvae and had then pupated there? When the adults emerged, some of them might take a wrong turning and up inside the house. That would mean that there would have to be a permanent pool of water nearby that was well supplied with rotting sediment. I opened the window and saw, directly underneath, a clogged gutter, brimming with water and blackened leaves and moss. Q.E.D.

19. Bibionidae – nomenclature

Last week I tagged along with a fellow blogger (Rediscovering the moths of Whittingehame) to the Entomology collection of the National Museums of Scotland, no longer at the handy downtown Chambers Street Museum, but now kept in distant Granton. After a couple of hours working as a dogsbody, fetching trays of moths, counting them up and looking for any with “A.B.B” (Alice Blanche Balfour) on their label, I took up the offer from Ashleigh Whiffin, the Assistant curator, to show me some of the much more interesting fly collection. First I asked to see Volucella zonaria – the mystical hoverfly of my youth whose image taunted me from the front cover of Flies of the British Isles – and there it was, bigger and brighter than I had imagined.

My next choice was to see the trays for Bibionidae – March flies – since I had caught one a few days before and had a key to the family, and wanted to check that my identification was along the right lines. These are familiar flies of spring, mostly black and bristly and my kind of family with only 18 British species to decide between. It is a completely different experience going through a key when you can look at specimens with contrasting characters – so that it was easy to see that my fly was in the genus Bibio and not Dilophus in which the front tibia has a no-nonsense set of spikes at the tip. Some species in Bibio are very large or with bright red legs, all of which tended to confirm my identification as this one being Bibio johannis, a common Spring species in lowland Scotland.

But, my feeling of satisfaction at having identified a March fly was short lived. One of the volunteers told me that they weren’t actually March flies, but St Mark’s flies, the reason being that they appeared around St Mark’s day (25th April). That name and the explanation for it was confirmed by Flies of the British Isles, while the internet told me that in Australia, March flies are notorious biters and members of the family Tabanidae. Had I been calling them the wrong name all these years having misheard “St Mark’s” as “March”, just as for a long time I thought that one of the choruses in Handel’s Messiah was “A wee black sheep” (“All we like sheep have gone astray”). Or even better, was it like Dave Allen’s innocent boyhood improvement on the burial service “In the name of the Father, and the Son and in the hole he goes.” To my relief however, bibionids are known as March flies in America, and so I can blame my mixed parentage for my confusion – and the first sightings of Bibio johannis can be March – so everyone was right!

18. Dolichopodidae – proto punk

My photographic set-up doesn’t do it justice, but this is a tiny fly with flair – the top of the thorax is black set with tiny golden hairs. But with the light shining just the right way it glistens lime green down the centre with a purple sheen to either side. The sides of the thorax look much plainer, but again, in a slightly different light the surface shimmers with yellow, purple, pink bronze and green. It’s the same on the head and the abdomen, and even the wings glisten – only the legs are matt, though they are unusually long and quirkily bristled, and shoot off backwards as if the fly is leaping forwards.

This was an innocuous looking fly swept from a sludgy puddle in a tractor rut at the muddy edge of a field about to burst into oil-seed rape yellow. It reminds me that flies, like people, are always more interesting than you first suspect. For example, it doesn’t look like it, but this fly is a predator that mashes up even smaller insects with its innocent-looking mouth. The males of many species in the family have extravagant legs with brightly coloured combs or unusual twists and swellings, while others, like one I caught 30 years ago, have exuberant genitalia hanging down from the tip of their abdomen.

In human terms, these show-off flies have pre-empted disco-glitter jackets, sequined blouses, flared trousers, finger bling, skinny-fit trousers, garish leggings and baroque codpieces – anything to catch the eye of the other sex as a prelude to coupling on the edge of a muddy field. The world of fashion is along way behind these proto-punk sexual predators.

The one I caught is less dramatic, but on its middle leg the first tarsal segment (the tarsae are the segments that come after the femur and tibia) short and slightly bent.

17. Limoniidae – unlocked key

18th April 2019

As a brave schoolboy, newly fixated on Diptera, I contacted the Entomology department at the National Museum of Scotland in Edinburgh and arranged to borrow some identification keys that were either out of print or prohibitively expensive for me to buy. I was ushered through a locked door on the public galleries to the cramped innards of the museum where the curator, Mr Pelham-Clinton, led me between ranks of wooden cabinets and, somewhat guardedly, handed over his personal copies of keys to the Syrphidae (hoverflies) and Tipulidae (craneflies). I laboriously made imperfect photocopies and returned the originals, not getting a second chance behind the scenes.

These were not easy keys to use, as I was reminded when, older and wiser, I tried to pin down a new fly from the ice-house. This was a much larger, longer-legged and speckled-winged fly than the winter gnat (Trichoceridae) that I had started off the year with. From the family key it was Limoniidae, equivalent to the subfamily Limoniinae in the museum key (Coe 1959).

The first couplet was: 1. Antennae 14 segmented …. or antennae 16 segmented – I made it 15. I counted again – still 15, including the tiny terminal segment. Now what? The first choice was actually “Antennae 1. 14 segmented and r always present” – but what on earth was “r”? No explanation was given there or in the general introduction. Presumably “r” was a vein of the wing since there was an R vein, but no “r” was shown on any of the wing diagrams. Unhelpfully, in my other boyhood book, Colyer and Hammond’s Flies of the British Isles, the wing veins were numbered rather than given letters, and there was also the less than enthusiastic endorsement of the Coe key: “Identification of the British species of crane flies may be essayed with the assistance of Coe”.

As a boy that would have been the end of it, but these days with a bit of hunting about on the internet I turned up copiously illustrated online keys to the subfamilies of Limoniidae (by Mike Hackston) and to the genera and species (by Alan Stubbs and John Kramer) which not only showed me which vein was “r” but easily guided me through clear-cut choices to Limonia nubeculosa. There was also the reassuring information that the three obvious dark rings on the first section of each are “unique among crane fly fauna of British Isles”, while the Coe key belatedly told me that the species is very common in woods, widely distributed and flies from February to November. Mr Pelham-Clinton would have been pleased to know that I got there eventually.

16. Anthomyiidae – schism

Two smallish flies that I assumed were house flies (Muscidae) managed to find their way into an unbaited double bottle trap by the compost heap. But, to my surprise, both turned out to have fine hairs on the underside of the scutellum – the hind tip of the thorax. In the picture the scutellum is in the middle of the image with two thick bristles, and a moustache of much finer hairs beneath. The flies also had a long anal vein (the penultimate vein on the hind margin of the wing), a combination of characteristics that marks them out as members of the family Anthomyiidae (antho: flower, myia: fly).

My first thought wasn’t so far out since my treasured copy of Colyer and Hammonds’ Flies of the British Isles (Second edition 1968) gives Anthomyiinae as a subfamily of the family Muscidae. That’s Anthomyiinae with “inae” at the end (so a subfamily) rather than Anthomyiidae with “idae” at the end (to indicate a family) – a subtle distinction! Similarly, The Natural History of Flies by Harold Oldyroyd (1964) briefly mentions the larvae of Anthomyia procellaris and Anthomyia pluvialis (both now in the Anthomyiidae) as being members of the family Muscidae. However, the same author’s key to the Diptera (third edition, rewritten and enlarged, 1970) gives Anthomyiidae as a family, as also does the key to the Muscidae by D’Assis Fonseca (1968), and, definitively (for the moment), my Christmas present pride and joy, the lavishly illustrated, informative and accessible The European families of the Diptera by Pjotr Oosterbroek (2006). Lucky for me, I have another family under my belt.

Wikipedia entry: image Max Naylor

Of course, nothing material has changed just because taxonomists have given this group of flies their own family – anthomyiids still look rather like house flies; only the pigeon holes have changed, not the flies. Dare I make a comparison with the current political convulsions over Brexit? Whatever their result, it will be a long time before the mudflats and salt marshes of Doggerland return. The British Isles will remain where it has been for all of human history – part of the European continent, yet awkwardly separated from it, a suspicious observer and faltering participant; ever the wallflower at the party.

15. Simulidae – memory lane

We all have our weaknesses – two of mine are flies and books, so how could I resist finding a home for a copy of the attractively titled “British blood-sucking Flies” by Edwards, Oldroyd and Smart (1939) which was being discarded by my University Department? There were keys to each family, numerous line drawings, detailed species descriptions, two appendices and 42 colour plates. At the bottom of the last page, upside-down, is the signature of B.P. Marmion who was Professor of Bacteriology at Edinburgh University in the 1960s and 70s when I was a schoolboy. The Department of Bacteriology became that of Medical Microbiology which is where I worked for a spell, several Professors later. Coincidentally, he had previously been at the Pathology Department at Cambridge University where I did my PhD, at the Walter and Eliza Hall Institute in Melbourne, Australia where I did my first post-doctoral research, and one of his research interests was hepatitis B virus – while I worked on hepatitis C and hepatitis E virus.

This book has been sitting on my shelves for twenty years now, still little read, until today when I was able to use it to identify a fly brought to me by the chap who has the office above mine. Notably, we have been friends for 45 years since we met at school, both avid members of the school Natural History Society, the highlights of which were weekend expeditions to the country cottage of our Biology teacher, Mr Faithfull. In the photo I am wearing the green and yellow jacket and he is sitting below me to the left. For all those years we egged each other on in a series of semi-serious competitions – cross-country running, stone throwing for distance, accuracy and bounces, bird watching, living things in our gardens, moth trapping, moths without trapping and landing on Scottish islands.

The tiny fly in question is a member of the family Simulidae, commonly known as black flies, and notorious biters. The veins in their wings are distinctively stronger at the front edge, and the thorax looks huge and muscular compared to the tiny head tucked under at the front and the stumpy abdomen at the rear. This fly was biting my friend’s neighbour’s horses and is a female. Going through the rather sparse key (which happens to be for females only) in “British blood-sucking flies”, I conclude that it is Simulium variegatum rather than the typical horse-pest S. equinum or the more common S. ornatum. The chapter’s preliminary text on the family notes that attacks on humans are not usually serious, with few reports of fatalities, although in Africa they act as vectors for the parasitic worm Onchocerca which causes river blindness. My only encounter with them in numbers was in New Zealand where they are known as sandflies. Setting up camp by a river one evening I wondered why my hair was starting to feel damp and sticky. The flies approach silently, make an incision with their scissor-like mouthparts, and secrete an anti-coagulant to prevent the blood clotting while they lap it up from the wound – my hair was damp with blood, and I quickly retreated to the tent, no match for the fly, another weakness I am happy to admit to.