Snow fleas, a species of springtail, are not a type of flea. Neither are they insects, though they are close relatives. During most of the year they live in the soil and leaf litter, consuming fungi and decaying vegetation. On warm winter days they appear on the surface of the snow, and are often described as “pepper on snow” due to their black color and tiny size (1 – 2 millimeters long).
Although they lack wings, they have two tail-like spring projections, or furcula, which are held like a spring against the bottom of their abdomen by a kind of latch. When the snow flea wants to move, the furcula springs downward, catapulting the snowflea as far as 100 times its body length. Snowfleas in the genus Hypogastrura possess three pinkish anal sacs which are usually located inside the snowflea, hidden from view. Just before jumping the snowflea everts these sacs from its anus. Their function has not been confirmed, but many biologists believe they serve as a sticky safety bag which prevents the snowflea from bouncing around when it lands.
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