Wednesday, June 8, 2016

Golden-Backed Snipe Flies

A female Golden-backed Snipe Fly

     Flies are rarely considered beautiful and are mostly looked upon with disdain, but there are thousands of kinds of flies, some with fascinating life histories and others which are quite attractive. Take the Golden-Backed Snipe Fly (Chrysopilus thoracicus) for instance. This is indeed a handsome fly. Found during late spring through early summer, these flies are quite noticeable due to their bright coloration.
     All of North America's 32 species of flies in the Genus Chrysopilus are bright colored. The Genus name actually translates to "golden-hair" and this is a distinctive feature. The species name thoracicus is said to refer to the slight striping along the thorax. Both of these are thought to help mimic a bee or wasp, which tend to be avoided by many predators since they may be able to sting. This may offer some protection to these flies.

A female Golden-backed Snipe Fly pretending to be a bee.

     Golden-backed Snipe Flies are harmless however. They inhabit deciduous woods, often either sitting facing downwards on a tree trunk or sitting on low foliage. Since other species of Snipe Flies (Family Rhagionidae) are predatory as adults (some even bite), Golden-backed Snipe Flies are believed by some to prey on other smaller insects as well. But that has not been proven. Some other experts think the flies may not even feed as adults. 
     As in most flies, the females are larger and more rotund than the males. This is so they can carry more eggs. Male Golden-Backed Snipe Flies are thinner and have what are referred to as holoptic eyes. Their eyes seem to almost meet in the middle top part of their heads, the better to see females with. The male hooks himself to the rear end of the female, facing away from each other. They can stay in this position for hours. If they are disturbed, the female will often carry the male in this position a short distance before landing again, never breaking contact. 
     The life cycle of Golden-Backed Snipe Flies is not well known. Since other snipe fly larvae are predatory and can live in moist wood, perhaps that's the case with these. But that discovery has yet to be made. It just goes to prove how little we really know about the natural world and how much more we still have to discover, even about common and colorful creatures such as these.

A male Golden-backed Snipe Fly, note how the large eyes almost touch and how thin it is compared to the more robust female in the first photo.

1 comment:

  1. We live on the edge of a wooded area with a creek running through it. I never noticed the fly until this year, and have seen them resting on several plants and shrubs. One just landed on my tablet, giving me a close-up view...quite beautiful!