Snow scorpionfly


Boreidae, commonly called snow scorpionflies, or in the British Isles, snow fleas 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, 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. The males use their bristle-like wings to help grasp the female over his back while mating, while the wings of females are vestigial small oval pads with no ability to allow her to fly. The adults have a long rostrum formed from the clypeus and labrum, genae, and maxillo-labium.
The body temperature, and therefore activity level, of this scorpionfly depends on its absorption of short-wave and long-wave radiation rather than surrounding air temperatures. The boundary layer of snow that the insect occupies has very low thermal conductance, and so the insect loses its own heat very slowly here. This delicate balance between cold and heat means that the animal is easily killed by heat when held in a human hand.

Phylogeny

The cladogram of external relationships, based on a 2008 DNA and protein analysis, shows the family as a clade, sister to the Siphonaptera, and more distantly related to the Diptera and Mecoptera.

Genera

This list is adapted from the World Checklist of extant Mecoptera species, and is complete as of 1997. The number of species in each genus is indicated in parentheses.