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Finale – the last post

31st December 2019

Well that kept me busy! The year of the Year of the Fly is almost over and what fun it has been – from sea caves to mountain tops and everywhere in between, I have inspected flowers, swept my net, sucked at my pooter and generally invited flies back into my life in every way that I could think of. I have baited traps with carrion and less pleasant items, headed for the woods with a fly in mind and come back with it, and been brave enough to meet some of the Titans of the fly world and found them to be, at worst, amiably eccentric, somewhat after my own bent.

Finding examples of 63 fly families was twenty or so more than I thought I would manage; writing that many blog posts was less of a slog and more amusing than I expected; an aggregate of more than 2000 views and almost 500 visitors over the year is something I don’t know what to make of; my assiduous readers from Portugal and Denmark – who are you?

I now have a tower of insect boxes each containing flies sorted into their families, arranged taxonomically and identified to species where I was able. Some groups require dissection of the genitalia which is a step too far for me just yet.

Each fly has its label recording the date and place and collector, and I have examined each one intently, scrutinising the pattern of its veins, the distribution of bristles on its legs, the jut of its face, the spread of its antennae and, when I had to, the baroque ornamentation of its privates. Where all that study resulted in a firm identification there is a second label underneath with the name of species and the day that I identified it. At first I was very cautious about committing myself in ink to such taxonomic decisions, but gradually it has dawned on me that these identifications can be corrected as I get to know each family better. Every once in a while the peculiar characters referred to in the keys excitingly materialise under the microscope and a new fly frontier opens. It is, like everything else, work in progress, hopefully largely accurate but no doubt imperfect, destined to be incomplete as a collection even as it gradually grows. It is a symbol of a year well spent, a late blossoming of my misspent youth. What, I wonder, did I do with myself before flies?

63. Pollenidae – a time of gifts

Among the greetings cards that turned up on Christmas Eve was a bulkier envelope with the latest copy of Dipterists Digest (Vol 26. No 2), this being the more scholarly of the two publications produced by the Dipterists Forum. Too my delight, under the heading “Corrections and changes to the Diptera Checklist (42)” by the Editor, Peter Chandler, there was the announcement of, appropriately for the time of year, that a new family had been added to the British list. A paper in Systematic Entomology – and hard though it may be to believe, they mean something more systematic that what I have been doing all year – with the punning title “Reclustering the cluster flies (Diptera: Oestroidea, Pollenidae)” had moved the genus Pollenia out of the family Calliphoridae and into its own family.

What a gift! I knew that I had collected some already, one in March that was attracted to a bottle trap baited with half a mouse, being one of the first bulky flies to be out and about. Then in October as things were tailing off, I caught several more sunning on the stonework of the house. These flies are cute in that they have wavy golden hairs on their thorax, an extravagantly sparkly coat that probably doesn’t do much to keep them warm as they cluster together over the winter in your attic. They are less cute in that they develop as parasites of earthworms, of which there are plenty in the garden despite the resident mole and robin.

Another Christmas gift was “A Dipterists Handbook” (also Edited by Peter Chandler) with an exotically-legged dolichopid marching across the cover. Inside, five hundred pages devoted to the history, collection, identification and study of flies. Glancing through I noticed sections on “Wetting dry flies” and “Drying wet flies” and chapters with evocative titles such as “Dung”, “Mud” and “Carrion” – I can hardly wait for Spring sunshine and for all those lovely flies to come back into my life. From flies basking in the garden with me to flower-filled meadows humming with activity to seemingly barren mountaintops there are always flies to be found; they are amongst the tumbled wrack on the seashore and they flit around rotting carcasses and collapsing mushroom caps, they are resting on tree trunks or hiding in culverts and caves, they come and find you (and bite you), they arrive, inadvertently on chips and in moth traps, they are hiding in the herbage or are flying past on their busy way elsewhere. They have led me on a merry dance – this year has been a gift of flies.

62. Brachystomatidae – incertae sedis

Here’s some wisdom from the world of flies – you are richer than you may realise! I have many unfinished projects, stuffed drawers waiting to be sorted, piles of boxes in the attic to be looked at another day. I should attend to them, if only to get them off my conscience, but there are always more interesting, tempting and lazier things to do instead, and so my material and physical burden increases year by year. The trick of course, if I only tried it, is to pick things off bit by bit – ten minutes of organising and chucking out buys you several hours of conscience-free time at the microscope.

And so it is with flies. I have flies in boxes that have been unidentified for more than forty years – I will get around to them eventually, if only to surprise some of the recording scheme organisers. More immediately on my conscience is the box of flies I collected during my week of fly ecstasy in Stirling and environs with the Gods of Diptera. There is a deadline of spring next year to get all the records in, and though I don’t expect to rival the experts in terms of notable finds, I want to make my own small contribution to the deluge of records that will be the result of that frenzied week.

My Stirling box is looking much emptier now that I have picked out the flies that are easiest to identify, but that means that the hundred or so left are tricky in one way or another. With some families I just write out the locality and date label and put the fly aside to deal with much, much later. This is the treatment for midges of all sorts, the equally tiny agromyzids and larger but inscrutable mosquitoes – will I ever get around to them? Some like chloropids, tiny shiny flies with triangles on their foreheads, I haven’t yet found a suitable key for and so they remain anonymous. And there are some families that I am frankly scared of – Phoridae, Drosophilidae and Mycetophilidae, for which I haven’t either a recent or a complete key. Then there are the 653 species of the miniscule gall midges Cecidomyiidae – those await a better microscope.

For some reason I had also been ignoring the Empididae, thinking they would be too hard. But when I sat down to tackle three caught in the woods at Loch Lomond, two were readily identified as common species. The third, a smaller, darker fly, had enormously extended antennae and also came out of the key with hardly a struggle as Trichopeza longicornis. I was just checking against some pictures online before happily filing it away with the rest of its family when I noticed a comment that the family for this genus was in fact Brachystomatidae, having been moved out of the Empdidae in 2006. The checklist confirmed this and noted that the taxonomy of Trichopeza was “incertae sedis“, meaning of uncertain placement, uncertainty which I am happy to embrace for the sake of my year’s tally. What else might be in that box?

61. Ditomyiidae – sun seeker

I thought I was done with fly families for the year – except for one up my sleeve which I was keeping as a finale. But a sunny afternoon drew me out from my struggles with annoying anthomyiids (bristles on legs, crucial features on hidden genitalia, awkward females, comparative adjectives without helpful figures, lots of head-scratching) for a walk through the woods. I checked out the icehouse where I bagged my first fly family on the first of January – Trichoceridae of course. There were no hibernating moths this time, but four Peacock butterflies, slivers of darkness, and one spreadeagled against the wall so as to scare me with its eye spots.

After several days of rainy deluges the river banks have been smoothed away, the vegetation toppled as if it had been scythed, the river still high and brown. As I emerged from the trees a heron lifted and croaked and floated away. This time of year the haugh is almost bare of flowers – just an odd yarrow parasol and fading bouquets of ragwort, but as if to compensate, the trees are in full colour – larch rich in yellow and russet, invisible the rest of the year but now the eye-candy across the river. At the spot on the banks where there used to be a bridge, two copper beeches were holding on to their leaves and catching the late afternoon sun. I settled myself amongst their comfortable roots and watched the river mumbling by, fidgeting in its hurry to be somewhere else. A dipper called as it whizzed upstream and in the other direction a buzzard mewed restlessly.

Ditomyia fasciata, female

There were of course no flies about, this being November, but I had brought my pooter along anyway, just in case. At the edge of my vision something flitted by and landed on the tree trunk above my head where the weak sun was warming the cold grey bark. I ended my sun saltuation and also that of the fly, the only one I saw apart from a twitchy blow fly that wouldn’t let me anywhere near it. Anispodidae, I thought, which was the third family of the year when it turned up in January in my bee shed, though the wings looked different with big dark patches – perhaps it was a different species. But under the microscope it turned out to have a different wing pattern, and it emerged from the key as Ditomyiidae, another family to have been hived off from the fungus gnats. There are only three species found in the UK, and this looked to be Ditomyia fasciata, seemingly unrecorded north of Nottingham. Nature’s way of telling me to spend quite so much time at the microscope.

60. Diadocidiidae – acolyte

Something I spotted from Peter Chandler’s spreadsheet of records from the Dipterists Forum field meeting was that there are quite a few families that are, to the innocent eye, just varieties of fungus gnats. The 1980 Royal Entomological key to the Mycetophilidae by Hutson, Ackland and Kidd mentions seven subfamilies, of which four are now considered as families in their own right (Bolitophilidae, Diadocidiidae, Ditomyidae and Keroplatidae), only the latter of which I had found so far.

My feelings about fungus gnats so far have been, initially pleasure at adding another family to my list, then appreciation of their distorted morphology with a hunched, almost apologetic thorax and tiny head in combination with enormously extended legs with poke-your-eye-out bristles, and lastly a relief at not having to tangle with any of their five hundred species again. This aversion was reinforced when I saw how the expert Dipterists dealt with their fungus gnat catch at the field meeting – they simply gave their specimens to Peter Chandler who identified them in production line mode using the vast key stored in his head. But if I was going to make it to bus-pass age numbers on my fly family challenge I would have to become braver, so I set off to get gnats.

At this time of year the woods are heaving with all sorts of nematoceran flies – crane flies, mosquitos, midges and gnats, a flystorm raining upwards from the disturbed undergrowth so that a few sweeps of the net resulted in a flutter of long-legged prisoners, most of whom could be safely ignored – I was after smaller prey. The haunts of gnats are damp hollows, rotten logs, muddy margins and so I crept about in all the dark corners of the woods, sweeping a tiny harvest with my net and pooter as the combine worked in the fields above. Back at the microscope I surveyed the catch which, as expected, were mostly Mycetophilidae, the largest family of fungus gnats. When you look at them closely they turn out to be subtly varied with a hint of character, wing spots, quirky bristles, shyly strutting their stuff – maybe I will come back to them yet.

Did you spot that the wings of last one are much less crowded with veins – there is a wide area of open wing at the base (a cell) and heading from it towards the wing tip a forked vein between two stronger veins – this is the hallmark of the family Diadocidiidae, and since there are only three British species I pressed on and am fairly sure that it is Diadocidia spinulosa. The larvae apparently live in mucous tubes under rotting logs, possibly associated with crust-forming and bracket fungi. Of the 40 previous records on NBN, there are none between one from the Black Wood of Rannoch, contributed by Peter Chandler, and a couple from Cumbria from a previous Dipterists Forum field meeting, no doubt also identified by him. I feel in august company.

59. Platypezidae – plod

I had a bad week. I was sent a spreadsheet recording all the flies that Peter Chandler had found during our Stirling fly week frenzy, and I discovered that, had I been more diligent, I might have added Bolitophilidae, Brachystomatidae, Ditomyiidae, Micropezidae, Pseudopomyzidae, Diadocidiidae, Pallopteridae, Therevidae, Platystomatidae and Platypezidae to my list of families. Of course, comparison is odious, and Peter, being an elder statesman in the world of flies, knows what he is doing, but all the same, I felt as if I had failed, or at least not done quite as well as I might. Having only found one new family in the last two months I was reduced to identifying hoverflies.

But just beyond my back door, creeping out of the forest floor as summer sidles off to become autumn, are suddenly a flurry of fungi, new arrivals poking their heads up to be greeted by adoring slugs, beetles and, I was hoping, flies. There are two techniques you can use. One is to take them by surprise, sweeping over the top and around the fungus honeypot and then pootering anything interesting out of the net. More satisfying is to get down to humus-level and wait for things to arrive.

At first there was nothing, everything having been scared off as I lumbered up and hunkered down, flat on my belly in a nose-to-gills stance driven by my short-sightedness, pooter at the ready. Hopefully there would be no passers-by to wonder if I was a corpse or to ask what I was doing. The rich black smell of rotting fungus flesh was quite strong and the ground wasn’t quite as dry, nor as comfortable as I had imagined. Partly filtered by the swaying tree tops, the grey sky began emptying itself. The uneven contours of my chosen fungus became familiar, a yellow mucous covered slab sinking earthward. My alert eye picked up tiny movements, but only of bugs, beetles and spiders. Then, darting out of a slug hole, dizzyingly circumnavigating the cap and disappearing again after some unexpected twirls and fancy footwork was a frenetic fly. Next time I was ready with my pooter and, eventually, potted it.

Nothing much to look at you might think, another dull brown fly. But do the wings not seem a little broader than strictly necessary or usual for such a little fly? And one of the veins at the wing tip arrives there after splitting off perversely from its proper direction. Even stranger, the hind feet are like a nightmare vision of what women’s footwear could be like with a properly sadistic designer.

What were these ladies (I only caught ladies) doing with these pumped up, awkward-fitting and faintly repulsive tarsi, like grey liver lobes? Might it help them from skidding around on the slippery surface of a mushroom? I doubt it. Perhaps in attracting a mate – tastes differ of course. Any explanation has to cope with the fact that in different genera it is either the males or the females that have these flat-feet (hence Platypezidae – flat footed flies). At least it’s an appropriate family to echo my own feeling of being a little slow on the fly front. Must plod more.

58. Conopidae – endgame

I have a confession to make. Until yesterday, I hadn’t found a new fly family for more than a month, and not for lack of trying. I have had two full days searching in prime Scottish habitats at the end of Dipterists Forum field meeting in Stirling, as well as several trips to different places in East Lothian; I have found lots of flies, but all in previously found families. The families that I am missing are mostly those with very few species, often obscure flies at the limit of their range in southern England and that I wouldn’t expect to come across. A few others are parasites of bees, bats or birds and will require a bit of specialist help to find. However, there are three reasonably common families that are still missing from my list – Conopidae (Thick-headed flies), Therevidae (Stiletto flies) and Platypezidae (Flat-footed flies) – and I thought that if I knew where to look I might be able to turn them up.

The larvae of Conopidae are parasites of bees and wasps, the adults then feeding on flowers, with the females waiting for a victim to turn up before pouncing on them, prising their abdominal segments apart and injecting an egg. So one sunny day, getting tired of my labours in the garden, I took a walk down to the river where I knew there were some good banks of flowers. There were lots of hoverflies and tachnids, as well as butterflies, ichneumon wasps, beetles and then for a moment a wasp that wasn’t quite a wasp, long antennae at the front, and I kneeled down for a better look, regretting not having a tube or a net in my pocket, but memorising its features before it took off – black and yellow striped abdomen, slightly waisted and swollen at the tip, a black thorax with yellow spots at the shoulders. When I was almost back at the house I spotted another one on a patch of thistles, rushed back for my net and with a bit of persistence, located and caught it.

Conpus quadrifasciatis, male

There is something about this fly that reminds me of Tom the cartoon cat – though I am not sure I can explain why! Perhaps it’s the ridiculous antennae (like ears?), the elongated proboscis, the enormous head and general look of bumbling purposefulness. In any event, this is a superb fly and should it happen to be my last new family for the year it would be a fitting way to finish, though I haven’t given up yet!

57. Ptychopteridae – details

I like this fly. There are some eye-catching craneflies – the yellow and black Nephrotoma and the boldly wing-patterned monster Tipula maxima, others with speckles or smudges, a few species with weirdly branched and asymmetric antennae, all these from the family Tipulidae. However, even their fiercest admirers would have to admit that most craneflies tend towards the dull end of the spectrum. Not this one – a glistening jet-black body, boldly blotched wings and a slender abdomen that needlessly bulges out and then tapers off again to a purposeful looking spike – and there is more!

Hoverflies are notable for having a spurious vein in the middle of their wings – this is a ghost vein that doesn’t have a proper start or finish and is much lighter than the other veins, sometimes almost the same colour as the wing membrane so that you have to tilt it to just the right angle to see it. This crane fly has two spurious veins – one that runs through the big blotch in the middle of the wing, which is hard to see, and the other near the trailing edge, where it sits at the bottom of a wing gully. No doubt these spurious veins have something to do with aerodynamics, a pleated wing having different performance characteristics than a flat surface – but how are they formed if they aren’t pumped up like all the other veins when the adult emerges from the pupa with stubby, half-formed wings?

Another curious feature of flies in this family concerns the halteres, the stubby lollipops that are all that is left of what were once a hind pair of wings. Halteres are also called balancing organs and are vibrated at the same frequency as the wings, helping the fly to monitor and correct its flight, like little gyroscopes. In this family, the halteres have an unusual thumb-like projection at their very base. Going through the family key I have looked for these projections on a lot of flies which, until now, have always had simple halteres – so it’s nice to finally see them, and to wonder what they are for – I suspect that no-one knows. It’s always a surprise how quickly you get to unknown territory with flies. In many families the larvae are unknown and so is their food source. Sometimes the adult males are missing, and for many species we have little idea what the adults up to and how they meet up to mate? There are great holes in the distribution maps, and even less information about how the distribution is changing. And I want to know what’s with the bulbous abdomen?

56. Ulidiidae – hidden meaning

I thought I was onto something special with this distinctively marked fly. There was nothing too hard about the route through the family key which brought me to a new family, and even better, it had very few genera and species which meant that I might be able to identify it completely. A poster fly for ease of identification, an easy acalypterate, a fly so full of character that it has a cryptic message written in fuzzy ink across its wings – nu on the left and un on the right – nu-un.

But when I went through online keys and checked out photos I was clearly on the wrong track – the best fit was a completely different looking beast with WaaW written across its wings, which is pretty much how I felt. Instead of being from an exciting new family, I must have gone wrong somewhere in the key and it was probably one of those spotty-winged tephritids. Except that none of the tephritid wing patterns matched, and the key character for the family, the Sc vein being bent at a right angle and fainter as it reaches the wing margin was not right (Sc is the thickish vein that curves up and just makes it into the top of the white part of the black U shape).

It turns out that the fly is a dead ringer for Herina frondescentiae, a member of the family Ulidiidae. Going through the key again, there should be two breaks in the vein that runs along the top of the wing. You can see one at the extreme left side of the wing, and there should be another roughly where the Sc vein meets the wing edge – but there is no sign any break there. Everything else about the fly is right – including its reddish face with silvery side patches and “distinctive” nu-un message – and although it wasn’t the family I first thought it might be (Platystomatidae), it’s still a new family – a new ‘un in fact!

55. Chaoboridae – metaphor

When is a mosquito not a mosquito? This fly in the family Chaoboridae, also known as a phantom midge, has the bottle-brush antennae you would expect to see on a mosquito (family Culicidae), but it lacks piercing mouthparts and so is not worth swatting away, unlike its similar looking but blood-thirsty cousins. The larvae, are notable for being predatory of other small aquatic creatures, including mosquito larvae, and also for being transparent, hence the names of ghost larva and glassworms.

Having nothing much else to say about the family, I find myself musing that we too are transparent in our younger versions, our needs easily identifiable, our pleasures simple, although sometimes rapacious. As toddlers, a butterfly bouncing by is a delight to be followed and grinned and exclaimed at, a technicoloured instance to be shared, and then possibly to be caught and crushed at which point our grief is deeply felt and widely shared. Nothing is a secret, at least not for long. Every few years we go through a different developmental instar with different kinds of endearing characteristics, before inevitably the seasons turn and we spin a protective cocoon for those awkward teenage years. Being neither fish nor fowl we rail at the world from within our self-inflicted shell at the humiliation of dependency.

One fine year we emerge and take wing as gangly-legged but gloriously-differently constructed adults, our bodies reproductively ready even down to the sex pheromones and gender-attuned antennae. But we are also now less transparent than we were, our response to a butterfly more complicated, seeing it as a connection with nature, a metaphor for the soul, an instance of God’s perfection, a focus for meditation, a harbinger of spring, a named species with a biological backstory, an aesthetic arrangement of colour, evidence for evolution, a household intruder, a tick on a list, a shared experience. No-one can see through us any more, so they imagine indifference where we are really lost for words, empathy where we are merely being polite, ulterior vampire-like motives where we are really harmless nectar-feeders. We have a hard carapace but are also delicate. Just when you think you have someone pinned down they slip away, a phantom person.