As I packed my outdoor teaching supplies into my car after a fourth grade bird communication lesson, I checked the temperature: high 20s, powdery snow, and a forecast that promised it would rise above freezing within two hours.
I grabbed my skis and poles and headed to a nearby trail. I had about an hour before I needed to drive to another school, and just enough time to glide across the snow before it became wet and sticky.
A few minutes into gliding, I noticed something unusual for winter: a spider on the snow.
I squatted to watch it amble along. A dark spider in the middle of a wide-open meadow seemed like a risky move with hungry birds nearby. But I had a time crunch, so I didn’t ponder it long and skied on.
In sunny sections, the snow began sticking to my skis. In those same spots, tiny snow fleas clustered in depressions caused by yesterday’s footprints.
These tiny arthropods are not fleas but springtails. They use a tail-like appendage to spring several inches in one go — which is even more impressive when you consider that it’s many times their own length. Can you jump 50 or 60 feet in one leap?
When you see what looks like black pepper scattered on snow or clustered on water, you are most likely looking at snow fleas.
I did not linger over those hopping critters because speed kept the snow from clinging to my skis. However, as a naturalist, I get distracted easily. Before long, I crouched again to observe a third species of bug: a snow fly.
These wingless insects have six long legs and an elongated body that looks like a mix of a crane fly and a spider.
While snow fleas feed on microscopic decaying matter, adult snow flies have been observed only drinking snowmelt, and scientists are unsure if the adults consume anything else.
When I head outside in warmer months, even a short walk to the mailbox guarantees wildlife sightings.
In winter, there is no such guarantee. A careful observer can find tracks or other signs of wildlife, but bugs are a category we usually, and sometimes gratefully, do not encounter.
Yet when temperatures creep toward freezing under bright sun, you can count on finding a bug on the snow.
How do they do it?
There are four strategies bugs use to survive winter. First, a quick note on terminology. When I say “bugs,” I mean a wide range of arthropods, including insects and arachnids.
A smaller group, known as “true bugs,” belongs to the order Hemiptera and includes aphids and cicadas. For the purposes of this piece, I am not referring to that specific group.
Now for the strategies: bugs survive winter in four main ways — lowering their own freezing temperature, going dormant, migrating or relying on the next generation. Which strategy they use depends on the species.
The bugs you see crawling on snow produce antifreeze compounds, typically glycerol, a sugar alcohol that lets them supercool. That means ice crystals do not form in their bodies until far below water’s normal freezing point of 32 degrees.
Species that go dormant, a state called diapause, also produce antifreeze. These include many beetles and butterflies, such as mourning cloaks, that survive tucked inside logs or behind bark.
Some species avoid freezing altogether by migrating. Monarch butterflies are well-known for this strategy. Certain moths and dragonflies do the same, leaving cold areas for warmer ones until spring.
And finally, the strategy that may seem most surprising to us humans: relying on the next generation. Many species do not survive winter as adults.
Yellowjacket adults die off in fall except for the queen. Aquatic larvae of some mosquitoes and damselflies survive under ice after the adults die. Many moths and butterflies leave behind eggs or pupae to carry the species through winter, including swallowtails and luna moths.
These tiny species offer big lessons on winter survival. The cold months are a time to shift our routines, not just endure winter, but enjoy it.
We can adapt by heading outside when it’s bright, layering up and staying active. And it’s also okay to tuck in like a butterfly behind bark during darker hours to rest.
To add to the fun, there is nothing quite like spotting a bug when you least expect it. I challenge my outdoor school students to do just that in the dead of winter, and they love the scavenger hunt.
They look for snow fleas, snow flies and spiders on the surface of the snow. They also peek behind bark and inside logs for dormant critters.
Noticing the tiniest creatures survive the biggest challenge of a season offers hope and excitement. It also sparks a curiosity that can become a source of warmth for years to come.
