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Family Boreidae - Snow Scorpionflies

Snow Scorpionfly - Boreus brumalis - female Snow-born Boreus - Boreus nivoriundus - male Mid-winter Boreus - Boreus brumalis - male Boreus brumalis - female Borne of snow - Boreus nivoriundus - male Boreus in Carlisle, MA - Boreus - female Boreus - female Boreus brumalis?  - Boreus brumalis - female
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Mecoptera (Scorpionflies, Hangingflies, and Allies)
Family Boreidae (Snow Scorpionflies)
15 spp. in 3 genera in North America; 30 spp. in the world, Boreus being the only genus occurring anywhere outside of the Pacific US(1)
body 2-6 mm
Adults dark-colored with an elongated rostrum ("beak"), long antennae, vestigial wings, and long hind legs adapted to jumping; female has a straight ovipositor about the same length as the rostrum, and tapering to a point; males have a blunt rounded abdominal tip
Larvae caterpillar-like but have no abdominal prolegs or conspicuous dorsal setae
Holarctic in overall distribution; in North America, AK to NB, south in the east to VA & TN, south in the west to CA & AZ(1)
Boreus are widespread throughout the Holarctic Region, with 12 spp. in NA, of which only two eastern (B. brumalis and B. nivoriundus)
Hesperoboreus (2 species) are restricted to the west coast from CA to WA
Caurinus includes two species: C. dectes(found in WA and OR), and C. tlagu (found so far only in AK)(2)
on surface of snow at high elevations in southern part of range; on snow in various habitats farther north
adults active from November to March in southern part of range; spring and summer in the far north (e.g. Alaska)
larvae and adults feed on leafy parts of mosses and liverworts(3)
In Boreus, the mating behavior differs from other Mecoptera and other insects: the male grasps the female with his slender, hardened wings and moves her to a position above his back, with the lower part of her ovipositor inserted into his ninth (genital) segment(4) (photo of mating Boreus brumalis); the female, on the male's back, has the base of her ovipositor contacting the tip of the male's upturned abdomen.
Boreus brumalis
Boreus nivoriundus

It was suggested that the Boreidae are more closely related to fleas than to any lineage currently included in Mecoptera(5), but now it seems that each fleas and Mecoptera as now defined are monophyletic groups after all(6)
Works Cited
1.World checklist of extant Mecoptera species
2.Description of Caurinus tlagu, new species, from Prince of Wales Island, Alaska (Mecoptera, Boreidae, Caurininae)
Sikes, D.S., and J. Stockbridge. 2013. ZooKeys 316: 35-53.
3.The Mecoptera, or scorpionflies, of Illinois
Webb D.W., Penny N.D., Marlin J.C. 1975. Illinois Natural History Survey Bull. 31: 251–316.
4.Scorpionflies, hangingflies, and other Mecoptera
Byers G.W. 2002. The Kansas School Naturalist 48(1).
5.Evolution of the Insects
David Grimaldi and Michael S. Engel. 2005.
6.Phylogenomics resolves the timing and pattern of insect evolution
Bernhard Misof et al. 2014. Science Vol. 346, 763.