Boreidae, commonly called snow scorpionflies, or in the British Isles, snow fleas (no relation to the snow flea Hypogastrura nivicola) are a very small family of scorpionflies, containing only around 30 species, all of which are boreal or high-altitude species in the Northern Hemisphere. Recent research indicates the boreids are more closely related to fleas than to other scorpionflies, which renders the order Mecoptera paraphyletic if the order Siphonaptera is excluded from it.
These insects are small (typically 6 mm or less), with the wings reduced to bristles or absent, and they are somewhat compressed, so in fact some resemblance to fleas is noted. They are most commonly active during the winter months, towards the transition into spring, and the larvae typically feed on mosses. The adults will often disperse between breeding areas by walking across the open snow, thus the common name. The males use their bristle-like wings to help grasp the female while mating.
A snow scorpionfly is so adapted to its cold environment, just holding it in a human hand will kill it.