A Different Snow Fly

Today I finally made it out on the ski trails. (I’ve reached a point where if I have a relatively flat, groomed trail to ski on and I don’t have to go too fast, I can manage to avoid embarrassing myself too badly.) We got about four fresh inches of now last night and the woods were beautiful. It was also a lot warmer than it was last week, with an air temperature right around the freezing point.

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While I was huffing and puffing along I spotted several wingless Chionea snow flies of the same type that I wrote about at length last winter, walking over the surface of the snow.

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When I was almost back, though, a different insect caught my eye – another tiny fly in the snow, but with one crucial difference from the Chionea ones.

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This one has wings! After doing a little digging, I think this critter is from a different branch of crane flies, family Trichoceridae. I couldn’t find a lot of information about them beyond the fact that they’re a type of crane fly that’s active in cold weather, but I’m still amazed by how many small insects and other arthropods are actually active in the middle of winter here if you keep your eyes open for them.

Snow Fly? What the Heck Is a Snow Fly?

Or, In Which I Discover Snow Flies and Am Once Again Amazed by How Weird the World Is.

On Valentine’s Day, while setting up luminaries for a romantic candlelight snowshoe hike, I discovered this little creature walking across the surface of the snow.

I’ve posted photos of unexpected winter arthropods before, but those spiders and caterpillars were not this active – when placed on the frozen surface of the snow they quickly stopped moving. What the heck was with this thing, then? Since when do insects walk around in below-freezing temperatures like it’s nothing?

Thanks to the good folks at BugGuide, I now know that this is a snow fly, genus Chionea. (If you see the little round knobs on its back in the photo, those are structures called halteres that are unique to flies.) It is a wingless fly (who knew there was such a thing?) and the only time it’s ever really seen is walking around on the snow in the winter. It’s presumed that being active in the winter helps it avoid predators, and it does this by having antifreeze in its bodily fluids. SERIOUSLY, THIS IS CRAZY, WTF IS THIS THING. Actually it gets even weirder – possibly the only thing weirder than being a wingless fly with antifreeze for blood is being a parasite that specializes on wingless flies with antifreeze for blood, and according to Wikipedia there are nematodes that do just that.

You guys, nature will never stop making me freak out.