Semaphores

Semaphore Fly (Poecilobothrus nobilitatus) – male

A visit to the pond last Thursday afternoon yielded an unexpected addition to the list: our first Semaphore Flies (Poecilobothrus nobilitatus). When you see a male in action, it isn't hard to guess how the species got its common name. He does quite the fandango around the female, waving those white-tipped dark wings to attract her attention, then doing a series of fast flights back and forth over her, flipping himself over in mid-air so that he's always facing her. If she's impressed enough, she'll mate with him. And apparently, this male had the right stuff! By the way, when I say "flipping over", this isn't something we saw ourselves; it's one of the fastest known animal turns on the planet, and human brains and eyeballs don't process quickly enough to see it. But scientists with slow-motion cameras have recorded it. To us, it just looked like he bounced back and forth from one side of her to the other, always facing her when he landed on the vegetation. These little flies are predators, feeding on a variety of small aquatic invertebrates, including tiny worms, water fleas, and midge larvae. They're common and widespread in southern England and Wales, and slowly spreading north as climate change warms the islands. Elsewhere, they're widely found across much of Europe. Now that we know they're around, we'll be watching for them. Adults fly from May to August, so we still have a few months to enjoy them.

The female lacks colouration on her wings.