Comox Valley Naturalists Society

February, 2004
Frank Hovenden

Nature is full of surprises. Late winter is a time one would least expect to see insects. Yet as the sun gains strength and snows start to melt we get a chance to observe an insect which spends most of its life invisible, living in the soils, under tree bark and in the leaf litter of the forest floor.

Springtails are a small and primitive order of insects that exist in our forest soils in phenomenal numbers. Their scientific name is Collembola. These tiny insects, which are usually less than 5mm in length, exist in the millions per acre. They feed on decaying plant material, fungi and bacteria and thus play a role in incorporating this material into the soil. This is a role that is similar to that done by earthworms in our gardens. Many of our earthworms have been imported from elsewhere in the globe and they generally don’t fare well in the acidic soils associated with our forest lands. The springtails along with mites are the rulers of our local forest soils.

In late winter the springtail is often seen on the surface of the snow. To the naked eye they appear like flecks of black pepper, which jump around like a fleas, thus its common name, snow flea. The jumping is accounted for by a unique structure for locomotion possessed by this insect. It is called a “furcula”. This is a twin pronged structure that hinges at the end of the springtail’s abdomen. It is folded under the insect and held there under pressure by a clasp. It can be released suddenly to send the insect flying through the air much like a jumping flea. As a primitive insect, springtails do not possess wings, which would be an impediment for life largely spent underground. The furcula gives it a quick getaway mechanism to escape predators. It allows it to jump 20 times its length. It’s as if a human could jump 120 feet in a single bound!

You may ask what these insects are doing on top of the snow? In late winter after a few thaws, snows get dirty, for a lack of a better word. This means that the detritus of winter starts to form a layer on the surface. This in turn encourages bacteria and algae to grow. The red tint found on spring snow is an example of an algae growing on the snow’s surface. This thin layer of algae and bacteria is the food that the springtails come to the snow surface to feed on.

This insect lives in the soil, so how does it get to the snow’s surface? As the snow starts to melt, water runs down plant stems and stalks to the ground below, forming conduits. Think of the tree wells, but on a smaller scale. These tunnels allow the springtail to emerge from below the snow to its surface. The insect climbs up the plant stalks to the surface where a smorgasbord awaits on the snow.

If you are looking for springtails choose a warm sunny winter day. Look for dirty snow that appears to be moving. A hand lens will give you a good look at the springtail. If you wish to view its special structures, a microscope is required.

Soils are a medium often taken for granted, to the extent of being called dirt. However without healthy soils, vegetation and all terrestrial life would not exist. A world of strange critters visible through a high-powered lens exists underground. Springtails are just one of many life forms that exist unnoticed underfoot yet performing a vital ecological function.

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