Insects and spiders on the snow
After a November that was much colder than the usual — The average for November 2014 was 21.8 degrees while normal is 28.4 degrees — we were followed by a December that was also unique, but this time the temperature averaged way above normal. Until the last few days of the month, December 2014 showed an average temperature about 20 degrees above that of December 2013 and about 10 degrees over the norm.
It is very unusual for November to be colder than December. This year it appeared as though these months had reversed positions. November not only had a temperature more like that of December, it also had as many days below zero. Snowfall for this second-to-last month was above normal, 16.4 inches, while the precipitation of 0.98 inches was below usual.
This tells of the cold temperatures and the snows that we did get were the dry powder type, more conducive to December. December, on the other hand, had a warmer temperature, but also showed more of a November character when it came to snowfall. December gave us less than 10 inches of snow, about half the normal. The precipitation for the month, however, was above normal. The snow that fell this month was wet and we even received some rain.
Thanks to the early freeze-up and snows of November that lasted over the ice and frozen ground, we did keep at least some snow on the ground for the entire month. The dozen days with temperatures above freezing, even three days over 40 degrees, caused changes with the snow. Much of the snow cover that we had received earlier melted and that which fell on such days was very wet.
As always, the critters living here with us in the Northland respond to such a December as this. And so I was not really surprised to receive an email question recently with a photo attached of a spider on the snow. The observer asked what kind of spider it was, but also why was it out here on the surface of the snow.
Spiders and several kinds of insects can be found on the snow during mild days of all winters. Some, like this meadow-running crab spider that I was asked about, are probably left over from the autumn populations. But others remain active all winter under the insulation of the snowpack. When temperatures allow for it, as happened in many days of this December, they rise to the surface and move about. Despite their tiny sizes, most are dark in color and show up on the surface of the white snow blanket.
About the time that I received the inquiry of this critter on the snow, I found several more. One spider and three kinds of insects seemed to be living a normal life on top of the snow in these 30-40 degree days. Each kind has its own story.
At the edge of a pond on which I was walking, I noted a dark spider. Collecting it in my hand for a closer look, I was able to recognize it as a wolf spider. Several kinds of spiders live through winter almost as though it is just a regular part of life. Protected from the cold beneath the snow, mostly in leaf litter, they spend winter as adults and subadults. In typical spider behavior, they are alone on the snow and on the move. Maybe they find travel above the snow easier than below.
Among the insects that I saw, two were crane flies. Unlike typical insects, they reach maturity at this time. One, the winter crane fly (Trichocera), has wings and can be confused for a mosquito, but no, they do not bite. Its cousin is without wings and so is known as the wingless winter crane fly (Chionea). They are typically seen walking on the snow. Sometimes these walkers have been confused for spiders, but as insects, they have six legs, not eight.
Once again, the question of why they are here is pertinent. I have observed their mating on this cold substrate a few times, but mostly they just appear to be moving, maybe feeding. I suspect they will be with us for the rest of the winter and we have not seen the last of the mild days, nor of these crane flies.
Perhaps the best-known of insects on the snow are the tiny — barely visible — dots of springtails. Also known as snow fleas, they come up from below to hop about, feed and mate on mild days. They are more common in late winter and often cover the snow with an appearance of hopping pepper.
So, if you are out moving on the snow on a mild day, mostly 25-35 degrees, and you see what looks like insects or spiders, you probably did see them. They are a regular, though a bit unusual, part of the Northland winter scene.
Retired teacher Larry Weber is the author of several books, including “Butterflies of the North Woods,” “Spiders of the North Woods” and “Webwood.” Contact him c/o email@example.com.