Buttercup Blacklet

Today was the first of the month's two Bank Holidays. To me these are and always will be May Day and Whitsuntide, but officially they're called the Early May and Spring Bank Holidays. This shows a depressing lack of imagination, if you ask me, but sadly no-one did. There are a couple of villages near here that still have maypoles, and presumably people dance round those on the Early May Bank Holiday, if they're not marching about waving banners to show solidarity with international workers, or lighting Beltane fires, or some riotous combination thereof. But rather than dancing, marching, or fire-raising, R and I decided to observe another traditional English Bank Holiday ritual, and weeded the garden. Eeeeurgh. By the time we'd packed away our tools I was extremely grumpy, and it took half an hour of bug-bothering to restore my equilibrium.

Because it's May we've temporarily stopped mowing the grass (though I made sure it was very tidy at the end of last month, in the hope that I won't have to fend off neighbours offering to send round their husband/grandson/nephew to cut it for us, as I did last May), and the wild flowers are beginning to bloom. Right now the buttercups are doing especially well, and every time I tiptoe daintily through a patch of them I notice that many are occupied by small black hoverflies. 

These are Cheilosia - a difficult genus because in the UK it contains close to forty species, many of which are only distinguishable by microscopic examination, but if it's on a buttercup, and, like this male, it has pale tarsal segments in its front and middle legs, you're allowed to say that it's Cheilosia albitarsis, the Buttercup Blacklet. Or, at least, you can say Cheilosia albitarsis agg., because Cheilosia ranunculi looks almost identical. You can just about distinguish them from the shape of the final dark tarsal segment of the front foot, but that's not clearly shown in this image, so I'll have to stick with the 'aggregate' identification. I think he's a rather smart little hoverfly, with his metallic black thorax, golden wings and two-tone legs. He's about 1cm long, with a wing length of between 7 and 9mm.

By the way, the reason this 'white-footed Cheilosia' is the Buttercup Blacklet, rather than the cousin whose binomial actually mentions the plant, is that it's known that Cheilosia albitarsis larvae develop in the rootstocks of creeping buttercups, while the larval foodplant of C. ranunculi - though thought to be a member of the buttercup family - hasn't yet been definitely identified. Both sexes of both species will take nectar from a variety of plants, but any female laying eggs on a creeping buttercup like this one is likely to be C. albitarsis.