On a warm afternoon this winter, keep an eye out for snow flies walking on the snow. Snow flies are typically a yellow brown to light brown fly with a body of about one quarter inch long, not including their long legs. Snow flies are wingless – scientists assume that they lost their wings because it takes too much energy to fly in winter. However, being wingless makes the snow flies more at risk of being eaten by predators. This may be why we see them in winter when there are fewer predators out. Snow flies are similar to woolly bear caterpillars and wood frogs, in that their bodies produce a natural antifreeze that prevents these small insects from freezing during winter.
Little is known about the life history of snow flies. Scientists have found that females lay eggs in the winter. In the lab, eggs hatch in as little as eight days or as long as three weeks. But where the female lays her eggs, what the larvae eat, how long the larvae take to develop into adults, and where the larvae or adults live in winter remains a mystery.
Snow flies are related to crane flies, like the above giant eastern crane fly (Pedicia albivitta). You may have seen a giant eastern crane fly clinging to window screens in the late summer. At first glance, you might have thought it was a large mosquito. But if you look carefully, you will notice that the crane fly does not have a proboscis – or tube mouth – like a mosquito. Since they can’t bite you, it is safe to hold them in your hand to take a closer look.
One common New York snow fly is Chionea scita that was first described in 1848. The translation of this fly’s scientific name is snow (chion in Greek) knows (scita in Latin).
If you see any snow flies this winter, please let us know!
BugGuide Chionea scita
Byers, George W. The crane fly genus Chionea in North America, 1983. University of Kansas Science Bulletin.
Hansen, Amy. Bugs And Bugsicles : Insects In The Winter Honesdale, Pa. : Boyds Mills Press, 2010.
Schrock, John Richard. Snow Flies, The Kansas School Naturalist, Volume 38, Number 2 – May 1992, updated 2005.
Featured image: Chionea by MUSE, accessed from WikiCommons.