Boreidae, commonly called snow scorpionflies, or in the

British Isles The British Isles are an archipelago in the Atlantic Ocean, North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner Hebrides, Inner and Outer Hebr ...

, snow fleas (no relation to the snow flea ''

Hypogastrura nivicola ''Hypogastrura nivicola'' is a species of dark blue springtail. Its English name in the United States is snow flea, but there are also additional springtails (and insects) called by that name. They are unrelated to the more commonly known flea. ...

'') are a very small family of

scorpionflies Mecoptera (from the Greek language, Greek: ''mecos'' = "long", ''ptera'' = "wings") is an Order (biology), order of insects in the superorder Holometabola with about six hundred species in nine Family (biology), families worldwide. Mecopterans a ...

, containing only around 30 species, all of which are

boreal Boreal, northern, of the north. Derived from the name of the god of the north wind from Ancient Greek civilisation, Boreas (god), Boreas. It may also refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernand ...

or high-altitude species in the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

. These

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s 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. The males use their bristle-like wings to help grasp the female over their backs while mating, while the wings of females are vestigial small oval pads with no ability to allow them to fly. The adults have a long

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...

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 (by which it is completely unaffected). 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. The group has been proposed in some studies to be the closest relatives of

fleas Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, ar ...

(Siphonaptera), rendering Mecoptera paraphyletic. This has been disputed by other studies, which find

Nannochoristidae Nannochoristidae is a family of scorpionflies with many unusual traits. It is a tiny, relict family with a single extant genus, ''Nannochorista'', with eight species occurring in New Zealand, southeastern Australia, Tasmania, Argentina and Chile. ...

more closely related to fleas instead.

Phylogeny

It is unclear as of 2020 whether the Mecoptera form a single clade, or whether the

Siphonaptera Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, are ...

(fleas) are inside that clade, so that the traditional "Mecoptera" is paraphyletic. However the earlier suggestion that the Siphonaptera are sister to the Boreidae is not supported. The two possible trees are shown below: (a) Mecoptera is paraphyletic, Boreidae is sister to (

): (b) Mecoptera is monophyletic, Boreidae is sister to Pistillifera:

Genera

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

Boreus ''Boreus'' is the most diverse of three genera of insects in the family Boreidae. They are commonly known as winter scorpionflies due to their close relation to the true scorpionflies and preference for cold habitats. Description and distribut ...

'' (24) Latreille, 1816 (North America, Europe, Asia) ** ''

Boreus hyemalis ''Boreus hyemalis'' is an insect, 3 to 4.5 millimetres long from the family of ''Boreidae''. Its common name is snow scorpionfly, also known in Britain as the snow flea. It has stubby, grey-brown wings with a metallic sheen. Snow fleas crawl or ...

'' – also called the snow flea. * ''

Caurinus ''Caurinus'' is a genus of snow scorpionflies in the family Boreidae. There are at least two described species in ''Caurinus''. Species These two species belong to the genus ''Caurinus'': * '' Caurinus dectes'' Russell, 1979 * ''Caurinus tlagu ...

'' (2) Russell, 1979 (Oregon, Alaska) * '' Hesperoboreus'' (2) Penny, 1977 (United States)

References

{{Taxonbar, from=Q2004861 Mecoptera

Phylogeny

Genera

See also

References