At first we couldn’t believe our eyes.
A small gray object – actually several small gray objects – fluttered through the air looking like insects for all the world to see. But how could that be? It is winter. Isn’t this the season when most bugs take a breather?
My friend Bonnie and I, having recently gone for a walk on a warm, sunny day, got closer to get a closer look. We had to squint a bit to focus, but holy cow! The details were undeniable. head, thorax, abdomen; two antennae, six legs. Sure enough, we’ve been looking at honest insects! Flying! In the winter!
Our brain switched mode from observing to categorizing, and mine clicked on a group of creatures known as mosquitoes. Abundant in spring, summer, and fall, they look a lot like mosquitoes but belong to a family of their own — the Chironomidae, or nonbiting midges. They tend to be seen in small clouds (which are actually mating swarms), with an uncanny knack for flying around our heads and into our mouths and noses.
There was only one problem. I was wrong.
While the insects Bonnie and I observed had a pair of wings, just like mosquitoes (two wings are a hallmark of Diptera, or true flies), the beautifully veined structures were slightly larger than those of a typical mosquito. The legs were also longer. But at the time we were perfectly happy to accept the mosquito diagnosis and move on to other wonders on that gloriously warm day.
It wasn’t until a week later that I realized I’d gone boo-boo.
That day, my friend Valerie texted me a photo of a small, dark, wingless insect accompanied by the words “At LeRoy (Oakes Forest Preserve in St. Charles). Do you know what that is?”
I had no idea but was lucky enough to have my friend Google along with a few extra minutes. It didn’t take long to track down a likely suspect: a snowfly of the genus Chionea (an excellent scientific name, derived from chion, the Greek word for snow).
Well, I’d heard of snow fleas before, but snow flies? That sounded more like a sentence than the name of an insect.
It turns out that snowflies are pretty common, but often overlooked by people because of how we behave when the snow flies. Instead of the leisurely pace we adopt in mild conditions, our winter walks tend to be somewhat hasty and focused. We tend to miss the little details along the way.
And by little I mean tiny. The average length of a snow fly is 7 millimeters, which is just over ¼ inch. But this tiny body is packed with amazing adaptations that make life in and under the snow a breeze.
Snowflies can produce glycerin, a sugar alcohol that acts like an antifreeze, allowing them to go about their work in temperatures around 25 degrees Fahrenheit. In fact, when exposed to a heat source like a ray of sunshine or a warm finger, a snowfly will actually fly the other way.
Their dark bodies are easiest to spot when walking over white snow, but these insects typically spend quite a bit of time under the snow, hanging out in places like rodent dens. Living down under, so to speak, means that wings are not only useless, they are actually a disadvantage. And so these insects have none.
So how do we know it’s flies?
By looking at things like the mouth, eyes, leg segments, and places we would consider private, entomologists have determined that snowflies are part of the infraorder of insects Tipulomorpha – the crane flies. (You probably know mosquitoes, even if you don’t know it. They’re the summer flyers that look like giant gnats, with a wingspan of up to 2 inches, but don’t bite.)
And this is where our story comes full circle. Remember those bugs Bonnie and I found that I thought were some kind of mosquito? Guess what? They are also a type of crane fly.
As more was learned about snowflies, it was impossible to ignore the repeated mentions of other cold-tolerant insects, and pinnacle among them are small winged insects in the genus Trichocera, also known as winter beakflies.
Looking more closely at the photos I took, I could see not only the delicate, crane-like veining on the wings, but also two small structures beneath them called halters. These knobbed filaments, one on each side of the body, take the place of the hindwings and allow flies to maintain their balance in the air. While many different types of flies have halters, the easiest way to see them is on mosquitoes.
Well, can you guess which small, dark, wingless insect also has halters?
That’s correct! Although they don’t fly, snowflies have a tiny nub on each side of their body. Do the structures still have a balancing function? I do not know. But since snowflies move at 4 feet per minute, I suppose there’s a chance.
The next time you’re out and about on a warm winter’s day, don’t rule out encountering insects. Look for small gray objects fluttering through the air or black specks crawling across the snow. I bet you won’t believe your eyes!
• Pam Otto is the Outreach Ambassador for the St. Charles Park District. She can be reached at firstname.lastname@example.org.