Wing wavers

Hawthorn Fruit Fly (Anomoia purmunda)

While I was weeding in the garden the other afternoon, my eye was caught by subtle motion on a spike of vegetation nearby. Looking more closely, I found a group of small flies waggling their patterned wings at each other and occasionally engaging in a bit of spirited head-butting, trying hard to shove each other off the leaf. I've never seen a behaviour like it! It's a Hawthorn Fruit Fly (Anomoia purmunda), one of the so-called "picture-winged flies". These little insects measure a mere 4.5 mm (less than 1/4-inch) in length, but their frenzied wing-waving makes them pretty noticeable despite their tiny size. Those wings are distinctively marked too, with a big black splotch near the base and a couple of thinner lines further out. Their eyes, green with two pink stripes, are characteristic as well. Females lay their eggs in hawthorn fruits (though they'll use a variety of other species if hawthorns aren't available). Interestingly, though they were displaying on a shoot of Greater Periwinkle (Vinca major), that isn't one of the known larval host plants. These little flies are reasonably common in the southern half of England and Wales, and from Europe right across the Palearctic to countries bordering the Pacific. Adults are seen between July and October, so we may get the chance to watch them do their wing-waggling/head-butting thing again.