Insects In the Snow

INSECTS IN THE SNOW

Wednesday, March 14, 2007 (Napanee Beaver)

Friday, March 16, 2007 (Picton Gazette)

The cross-country ski tracks ahead of me appeared soiled, rather odd as I had just made the tracks an hour earlier, and was now on my way back. It was almost as if there had been a fire somewhere and this was black soot that had drifted in and settled in my tracks. But as I drew nearer, the soot began to dance as though activated by some mysterious static electricity.

Although the air temperature was near zero, the snow was still quite cold and was no where near melting. Still, these were minute insects I was witnessing – snow fleas actually, more accurately known as springtails, and they were in no pain. They’re used to playing in the snow.

Springtails, although resembling fleas as they jump about, are in no way related to fleas. They are so primitive they have no wings, and there is no evidence they ever did. In short, their evolution stopped long before wings came on the scene, and that was a very long time ago indeed. Springtails are aptly named, for that is precisely what they do, with their tail. It is an ingenious piece of equipment, forked and normally bent underneath the abdomen and fastened with a spring release under pressure. When released it hits the ground and propels the insect upwards, up to 100 times its body length. Handy for escaping enemies.

We always seem very intrigued when we see insects actively moving about in the winter. Woolly bears out on warm winter days never fail to shock us. So what are these snow fleas doing out? Warm winter days draw them out in large masses to feed on algae and fungal spores on old snowbanks. They are so tiny that 100,000 in a one square metre of surface is not an unusual number. When under the snow, they play an important role in recycling organic material. You can nearly always find a few if you look in the silvery fur of the winter rosettes of mullein. Interestingly, they have a tendency in winter to accumulate in low places; hence, the reason we see them in our foot tracks or ski tracks. If you want to get a close-up view of these little critters, simply take a look at them through the opposite end of your binoculars, which will turn your binoculars into a handy magnifying glass.

We call them insects, but actually they are not, although they are six-legged and certainly share a common ancestor. Their scientific name, Collembolla from ‘coll’, meaning glue and ‘embol’, meaning peg, refers to a rather fascinating feature about this creature. Don’t attempt to see this feature through the wrong end of your binoculars for you will likely fail in your attempt. They have a tube which projects down from the underside of the abdomen, and which exudes a glue-like substance for adhesion on slippery surfaces – certainly useful, I would suspect, if they are out and about on a windy day. That same organ also controls fluid balance in the body.

But springtails aren’t the only minute creatures that are apparent these days. The creeks that are flowing right now often produces stoneflies. Soon after hatching in early spring, the larvae bury themselves in the stream bed. The immature nymphs of these small, dark coloured slender insects live in water, and their name comes from their habit of clinging to the underside of submerged stones. When frigid weather sends virtually all other flying insects to death, the nymphs of winter stoneflies crawl from under their submerged stones where they have spent the summer, make their way up streambanks, and anchor themselves to rocks with gluelike secretions. Then, they crawl out of their skins, and take to the chilled air as four-winged adults. Check out your local creek and you may see them. If you are lucky, as I was last week, you may even see one flying at slow, lumbering speeds. They are welcome insects to see since they are indicators of water quality as they thrive only in clear, unpolluted water. In fact, when water-quality surveyors turn up stoneflies in their macro invertebrate samples, they classify the stream as “good quality” because these insects require clean, well-oxygenated water.

By having this rather unorthodox life style, and spending the summer lying dormant while other insects are out and about, they avoid problems like overheated streams, low oxygen concentrations, fluctuating flows, and heavy predation by fish.

With small birds and large predatory insects fewer in number in the winter than in summer, Springtails may even realize this too as they come out to dance in the snow. While I may have crushed several thousand springtails as I skied home, there were probably eight billion left behind that were untouched.

Now that the water in the lakes is beginning to soften up a bit, we can start thinking more in terms of animals emerging from hibernation and birds returning from the south. It seems hard to believe that tree swallows could be here in as little as two weeks, if the weather cooperates. And so passes another winter.