By PAUL HETZLER
They aren’t fleas and they’re not especially fond of snow, but other than that, snow fleas are aptly named.
On a sunny winter day you may notice tiny dark flecks bouncing on the snow, often concentrated near the bases of trees or collecting in footprints and other indentations. While snow fleas are the size of actual fleas, don’t worry about infestation—they’re not interested in either you or your pets (please don’t take that personally). Try not to step on them, though, as they’ve given us the means to improve both organ transplantation and ice cream.
Snow fleas, a type of “springtail,” were classified as insects until recent DNA sequencing pegged them as another type of arthropod called a hexapod. Apparently there’s now heated debate as to whether springtails qualify as a hexapod class or are merely a sub-class. You have to love scientists. First they study an obscure arthropod to develop life-saving technology, and then come to fisticuffs over labeling it.
Whatever the label, snow fleas are beneficial in many ways. As decomposers of organic matter, they’re important in the formation of healthy topsoil. They and their hexapod cousins are one of the most abundant types of soil ‘animals,’ numbering around 100,000 individuals per cubic yard of topsoil.
Besides eating algae, fungi, nematodes, protozoa and a wide range of organic matter, they consume organisms and spores that cause damping-off wilt and other plant diseases. In fact, springtails are being studied for their potential to control plant diseases in greenhouses.
Snow fleas produce a unique glycine-rich protein that keeps ice from forming inside cells at very cold temperatures. This newly discovered molecule is unlike any previously known protein, and is the basis for research on more efficient storage of transplant organs. Organs can be stored much longer at below-freezing temps with this antifreeze protein. Eventually we may also see ice cream that never gets ice crystals no matter how long it sits neglected in the freezer.
Springtails lack a respiratory system and must breathe through their skin. As a result, they’re quite vulnerable to drying out, and hop around to find moist, sheltered places as well as things to eat. A flea uses its tarsi, or toes, to vertically jump as much as seven inches, roughly equivalent to a person leaping 500 feet straight up. Using only their toes. The snow flea is not nearly as athletic. It either crawls, or uses its two tail-like appendages to bounce a fraction of a flea-jump.
During the warmer months, snow fleas and other springtails are even more active than in winter. It’s just that without a white background for contrast, we tend not to see them. Springtails forage extensively in the humus layer and move all through the soil, even deep down.
Springtails can be found throughout the forest canopy as well as on water, where surface tension keeps them from sinking. If you go out with a flashlight some June night you can see springtails bopping about on standing water.
Just the word ‘flea’ can set folks to scratching, so it’s unfortunate about snow fleas’ name. Try thinking of them as springtails, and keep an eye out on bright winter days for these jittery critters that help make topsoil, and could one day help save lives. Or at the very least, ice cream.
Paul Hetzler is an ISA-certified forester and a horticulture and natural resources educator for Cornell Cooperative Extension of St. Lawrence County.