Northland Nature: Winter crane flies active on snow

Jan. 19—Like many in the Northland, I was glad to see the snowfall of a couple inches in early January. Certainly, this was not a snowstorm, and it did not slow us down much, but a cover of a few inches of snow did open up things and allow for happenings that we had not been doing, or able to do, during the "snow drought" that we experienced during the previous weeks. Not only did we get the anticipated white blanket, but we also got temperatures that allowed it to stay.

Some winter sights and sounds that we had not had for a while returned. Snowplows, shovels, sleds, skis and snowmobiles all appeared again. We all have our own desires of what to do in this new snow. I was glad to go for a walk to note the tracks of passing critters that live here with us in winter and often do not get seen. And their messages in the snow were wide and diverse.

Walking the driveway, road and paths, I was able to locate tracks and trails of about a dozen local residents. Many I see nearly every winter walk, such as squirrels, mice, voles, deer, foxes, coyotes, shrews, rabbits and hares, but they were joined by a few others not seen as often: grouse, turkeys, bobcats, raccoons and skunks. These last two were of interest since they are likely to sleep through the coldest times. Other residents flew by: chickadees, nuthatches, woodpeckers, blue jays, crows and ravens, but not leaving tracks or footprints in the snow.

As I looked at the surface of the new snow, I noticed more. There was a winged critter, an insect, here that landed on the surface and was too light to make any tracks. I was seeing a fly, a winter crane fly (Trichocera). About the same size and shape of a mosquito, this insect belongs to the same order, Diptera, as does the mosquito.

A close look reveals that this one does not have the well-known proboscis of the blood-feeding mosquitoes. Indeed, these winter crane flies that I was watching do not eat as adults. As unlikely as it sounds, they reach maturity in winter after developing from larvae that live under the snow in the subnivean layer.

If the winter day is mild, the adults will go to the surface of the snow, take wing and search for a mate. The day was cloudy, calm and a temperature in the upper 20s, just fine for this insect to be active. After being photographed, it took flight again. During the subsequent days as the temperature dropped, these winter crane flies were not seen here. Apparently, they go into shelters either above or below the snowpack. They return with more mild days.

Trichocera is not the only insect that may be active on the snow in winter. Another crane fly that is wingless (Chionea) does much walking here as does a winter scorpion fly (Boreus). A few kinds of spiders, especially wolf spiders, may also be on the snow. And on some mild days, the snow is filled with an abundance of "snow fleas" (Collembola).

Other insects may be active in the moving waters of winter streams. Some of these will emerge onto the snow-covered shoreline. Stoneflies, caddisflies, mayflies and midges can be seen at these aquatic sites. (Immatures of these insects are aquatic and active at this time.) Yes, the snow surface is often alive with many winter happenings including insects and spiders.