Tag: Bibionidae

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.

Photo Katty Baird

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!

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!