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.
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.