A November surprise: Encountering a snow mosquito

The first of those was a bedraggled-looking daddy longlegs, which appeared to be in bad shape, and for good reason. As I’ve written in a previous City Wilds column (“Daddy longlegs offer all kinds of harmless surprises to those who pay attention”), these long-legged arachnids—which are also known in some places as harvestmen and shepherd spiders—don’t tolerate cold very well. In their adult form, the great majority do not survive winter, especially in frostier regions like Alaska, though their eggs do okay when deposited in places that offer insulation from winter’s deep freeze.

On this particular afternoon, temperatures had soared into the 30s, but not so many days earlier they’d dropped into single digits. Somehow this daddy longlegs had survived that frigid day, but it didn’t seem to have much remaining spark while stumbling across the snow on November 10.

I figured that barely moving daddy longlegs was my most impressive find of the day, perhaps even the month until, about a half-hour later, I discovered a mosquito sprawled out on the snow.

At first, I couldn’t believe my eyes.

Across four decades of residing in Alaska, I can’t recall ever encountering a mosquito this late into the winter season (which admittedly is still in its early stages). To be honest, I’m not sure I’ve ever noticed one even in October, though for most of my years here I didn’t take special note of mosquitoes—or other insects—once summer turned to fall and then winter. Only in the past decade or so have winter bugs become a fascination of mine. Or, some might say, an obsession. Speaking of which, I have now found one sort of Anchorage bug or another “out in nature” every month of the year since February 2012, a stretch of nearly 11 years, or 130 months.

But back to the mosquito.

When I first spotted it, the mosquito appeared quite still, as if it might be frozen. To be entered into my database—as informal as that is—it had to be alive and moving. To confirm whether that might be so, I gently lifted the mosquito from the snow into the palm of my bare left hand. From past experience, I knew that the heat radiating from my warm-blooded body would revive the insect, if she could be revived. (I also knew this individual to be female, her body shape and size and long, blood-sucking proboscis provided clear evidence of that.)

It didn’t take long for the mosquito to begin stirring. Then she stood. And in standing upon my hand, she reminded me of the large, slow-moving mosquitoes that are the first of their kind to appear in spring. Could this be one of them? If so, why was she active in November?

Moments later, she slowly buzzed off. But not for long. Away from my body’s heat, the cold air quickly reduced her wing speed and in a slow-motion kind of way, she dropped back to the snow.

I wanted to document my unusual discovery, so I again scooped the mosquito from the snow and repositioned her in my hand. Re-warmed, she again took flight and I again chased her down. Finally, on my third or fourth try, I got a decent picture of the mosquito in (cupped) hand, though I suppose one of her perched atop the snow (which I also documented on my iPhone) should have been sufficient.

I’ve been asked whether my repeated chasing of the mosquito and handling of her would constitute a form of wildlife harassment and I suppose it might. But in my defense, I’ll note that I also gave her a few moments of human warmth and enabled her to experience some additional flights through the frigid air.

I’ve also been asked whether I worried she might stick her proboscis into me when placed upon my naked skin and to that, I’ve simply replied, “No.” I’m not sure the mosquito was even capable of that, really. Though I suppose being bitten by an Alaskan mosquito in November would be an even rarer circumstance.

In any case, once I got a satisfactory picture of her I allowed the mosquito to buzz away one final time and wished her well as her flight path drooped and she floated back to the snowy ground.

And then I vowed to learn more. And I have.

It turns out that the mosquito I encountered is known to entomologists by the scientific name Culiseta Alaskaensis and in common English is called the “snow mosquito.” And, as I had guessed, “my” mosquito does (or did) belong to the species that is the first to emerge each spring.

As an aside, I’ll note that I also confirmed that nearly three dozen species of mosquitoes inhabit Alaska, the number given online ranging from 30 to 35, depending on the source. I suspect that’s many more than most people figure.

The snow mosquito is among those insects (and some other life forms) that successfully overwinter as adults through a process known as “supercooling.”

As a widely respected Alaskan entomologist named Richard “Skeeter” Werner once explained in an article “How Mosquitoes Overwinter in Alaska,” most species that live here spend the winter as eggs, deposited in various bodies of water by adult females. “These eggs then lie dormant throughout the winter until water temperatures are warm enough for hatching to occur the following spring.”

A notable exception is the snow mosquito—the largest of Alaska’s mosquitoes, Skeeter notes—which “overwinters as an adult under the snow, usually in leaf litter, beneath loose tree bark, or in dead tree stumps. This is the first species to emerge each spring, usually from mid-to-late April.”

In his 1987 article, Skeeter further noted that the snow mosquito’s ability to survive temperatures below freezing “is accomplished by two different biochemical processes. In the first process, the insect’s body water is replaced by glycerol, a type of carbohydrate, which acts as antifreeze and keeps the body cells from rupturing when temperatures reach the freezing point. In the second process, called ‘supercooling,’ the insect’s body temperature is lowered below the freezing point without its fluids solidifying.”

From other online sources, I’ve learned that overwintering snow mosquitoes can survive temperatures down to 25 degrees below zero (Fahrenheit), more or less. If the temperature drops below that, not even supercooling can save the insect. Of course, even when the air temperature drops to minus 30 or 40 or maybe even colder, a snow mosquito tucked safely beneath snow and leaf litter would likely be insulated from such extreme cold.

While most adult Alaskan mosquitoes live only a month or two (or less, if squashed while drilling for blood or eaten by birds and other predators), the snow mosquito may survive a full year or slightly longer; of course, much of her life is spent in winter dormancy.

As so often happens when a curious naturalist gains new insights into the lives of other creatures, additional questions naturally arise. For instance, I wonder why the snow mosquito I encountered came out of hiding. Conversely, given their winter survival mechanisms, why have I never before noticed snow mosquitoes in winter? It seems some must occasionally be buzzing about during winter warm spells, as the one I encountered this November was doing.

Skeeter Werner died in 2017, but I know at least a couple of other “bug experts” who might be able to give me additional insights and I’ll be following up with them. For now, I’ll be content to simply marvel at yet another wintertime wonder.

Anchorage nature writer and wildlife/wildlands advocate Bill Sherwonit is a widely published essayist and the author of more than a dozen books, including “Living with Wildness: An Alaskan Odyssey” and “Animal Stories: Encounters with Alaska’s Wildlife.” Readers wishing to send comments or questions directly to Bill may do so at akgriz@hotmail.com.