This winter has brought plenty of cold weather and snow, but the recent warm spell gives hope that spring is coming. Warming weather also brings out one of the most common land insects in our area, the snow flea or springtail.
These tiny creatures measure about 1/10 of an inch in length and are usually black or gray, though they can also be orange, white, brown or red. Their color and size cause them to blend in with the forest floor. As a result, they are hard to see except in late winter when they congregate on the white backdrop of snow.
Look for a patch of snow that appears to have pepper sprinkled on top of it. Many people will just pass by a patch like that, thinking it is dirty snow. But on more careful inspection, the specs of dirt will move. The springtail has two tiny appendages folded under the abdomen. A tiny hook holds the prongs in place until the insect arches its body, unlatching the hook. The prongs spring out, push against the ground or snow and propel the springtail into the air. It may travel a distance of 20 times the length of its body.
The jumping and the tiny size gives them the name snow fleas, but they are not related to fleas at all. "Spring tail" is a more apt name for this beneficial insect.
Fleas are annoying parasites, but springtails feed on decaying organic matter in the leaf litter, helping to recycle it back into the soil. They can actually stimulate a symbiotic relationship between fungi and certain types of plants, enhancing the plant' growth. Like many invertebrates, they are part of nature's waste management system, ensuring that the woods don't get buried in the mountain of leaves that are shed by hardwood trees each autumn.
Springtails are extremely abundant -- as many as 10 million per acre of forest. Despite their vast numbers, they are rarely noticed, because they spend most of the year beneath the leaves. When the snow begins to melt around the base of trees or other vegetation, they use these escape routes to climb out from under the snow and bask in the warm sunlight on the surface.
Congregations of springtails on the snow provide the best opportunity to notice and observe their behavior.
It surprises many people to think of insects being active in the winter, but the springtail has natural antifreeze called glycerol that helps it withstand temperatures as low as -7º F. Because it spends most of the winter beneath the snow, it is protected from the harshest weather by that insulating white blanket.
Springtails also move in warmer months. One summer while walking along a trail, I noticed a slight rustling sound on the dry leaves near my feet. I looked down and noticed a mass of specs leaping up and landing on the leaves, making pitter patter sounds. It was a group of springtails, the first time I'd seen them any time other than winter.
In the late winter or early spring, the female lays her eggs beneath the soil. Nymphs, which are miniature versions of their parents, hatch from the eggs and grow larger through the summer. This cycle is quite different from more advanced insects, which go through three or four stages of metamorphosis, changing their appearance, behavior and sometimes their habitat between the juvenile and adult stages. This is one reason that the wingless springtail is considered to be so primitive. It has also been around for about 400 million years.
So if warming weather isn't reason enough to get out, now you have something new to search for. Go hunting for springtails on your next outdoor excursion. When you find them, appreciate the fact that they are a sign of warmer days to come and a legacy of ancient times in the past. Not bad for a creature that looks like a spec of dirt!