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 and adults typically feed on mosses.

The adults will often disperse between breeding areas by walking across the open snow, thus the common name.

[1] The group has been proposed in some studies to be the closest relatives of fleas (Siphonaptera), rendering Mecoptera paraphyletic.

The two possible trees are shown below:[6] (a) Mecoptera is paraphyletic, Boreidae is sister to (Nannochoristidae + Siphonaptera):[6] Diptera (true flies) Pistillifera (scorpionflies, hangingflies, 400 spp.)