Snow Fleas
Have you ever taken a pleasant hike in the summer and autumn woods only to be pestered by annoying insects? By the time winter arrives, insects are smart enough to seek a warm place to sleep through the cold months. This rule is followed by 99.9% of all insects.
During the dead of winter, on a sunny day, there is an insect sometimes noticed on the surface of the snow. Snow fleas, which are neither fleas nor true insects, are more commonly known as springtails. Springtails are actually anthropoids called collembola, which comes from two Greek words: coil, meaning glue and embol, meaning a wedge. Both words come from the springtail’s ability to adhere to the underside of a leaf.
Springtails are primitive in that they do not possess normal insect legs, eyes or mouthparts. They are wingless and have simple eyes that only detect light or dark, while most insects have compound eyes. Snow fleas possess very unusual mouthparts that are contained inside the head rather than protruding on the outside like other insects. They have a very simple metamorphosis, going from eggs to nymphs to adults. However, what sets them most apart from other insects is their quirky method of locomotion. Although a springtail lacks wings, it has the ability to catapult itself by releasing two tail-like spring projections (furcula) on its abdomen. A springtail can fling itself over one hundred times its body length. In one study, it was found that the distance of springtail propulsion was found to be up to 12 inches. This is quite a feat since the snow flea is approximately 3mm long, which is the size of the period at the end of this sentence. The study concluded that springtails have neither control over the direction or distance of their flight, nor do they have a way to steer once airborne. After releasing the spring-loaded tail, the springtail is sent flying through the air without ability to control the direction of flight. Frequently, the springtail lands in the same spot or a small distance away.
Snow fleas are black and appear as pepper sprinkled on the snow. During the winter months when warmth from the sun heats the air, the snow fleas climb up through the snow to congregate on top of the snow, usually at the base of a tree, where it is slightly warmer.
A tree collects and releases the sun’s heat, causing the snow at the tree’s base to melt. These areas are known as microclimates (a small area with a different climate than the surrounding area).
Snow fleas can be easily seen on the snow, often at the base of a tree where it is slightly warmer
Although snow fleas are active throughout the year, they are more noticeable during the winter months when their black bodies show against the snowy background. To find snow fleas during the summer months, one must look closely at leaf litter, where they can be found hanging to the underside of leaves.
After mating in the spring, the female lays her eggs in the soil. The emerging nymphs undergo several molts. By the time winter arrives, they are the size of an adult.
During the summer and fall months, they live in the soil, feeding on decaying organic materials, bacteria, fungi, algae and pollen. They eat everything (including their own droppings) or nothing at all. In one laboratory study, it was found that springtails had gone without eating for up to four years.
There are over 6,000 known species of springtails. They are so adaptable that almost nothing man does will bother them. Springtails have been found in Hawaiian volcanoes and in the Antarctic.
The springtails can be active during a cold winter due to an antifreeze-like protein that is produced in their bodies. Scientists have found these proteins to be glycine rich and unlike any known proteins. There are hopes that creating similar proteins will be helpful for preventing the formation of ice crystals in the tissues of stored transplant organs. This would allow organs to be stored at lower temperatures, increasing their lifespan outside of a living body. Unlike other proteins, the proteins found in snow fleas break down easily at higher temperatures.
Since snow fleas do not have organs for breathing they must receive oxygen directly through their skin, which needs to be moist for an oxygen exchange to occur. This is why snow fleas need to stay in damp places, such as a sunny spot where the snow is beginning to melt.
When preparing to migrate millions of snow fleas can be seen on the surface of snow. Although this migration could only be a short distance, it could take several days due to their resting at night. Migrations take place when the food supply has been exhausted.
Thoreau wrote this about the tiny snow fleas, “A creature whose summer and prime of life is a thaw in winter.”
Larger insects feed upon the snow fleas, and in turn, these larger insects are eaten by birds, which are fed upon by larger predators. The little snow fleas are part of the food chain; however, they are also part of nature’s cleanup crew that cleans up the forest leaves that are turned back to soil.