Boreus nix Carpenter, 1935
Diagnosis: Body black and covered with long, white pilosity. Body length: male, pinned = 2.4 -4.1 mm; female, pinned = 3.3 – 4.5 mm; male, in alcohol = 4.3 – 4.5 mm; female, in alcohol = 4.8 mm. Ratio of length of maxilla-labial complex to rostrum = .88. Anterior and posterior margins of pronotum with 4 to 6 bristles. Meso- and metanota occasionally with two bristles; covered in long, white pilosity. Male wings abruptly narrowed at mid-length; with 16 mesal and 15 lateral spines. Hindwing with 10 – 11 spines. Female forewing oval, covering hindwing. Male 8th tergum and sternum not fused; 9th tergum and sternum also not fused. Hood of male 9th tergum relatively small, only about 1/3 width of tergum; medially, longitudinally cleft and with no medial ridge. Male 9th sternum with apicomedial notch.
Distribution – Geographical: This species is known from western Montana northward to British Columbia, and southern Alaska.
Distribution – Temporal: Adults have been captured from 2 November until 15 April.
Ecology: The dry mountainsides east of Hamilton, Montana, appear to be considerably different from the moist areas near glaciers at McCarthy, Alaska, but these seemingly different habitats may be ameliorated by microhabitats and different dates of adult emergence (later in Alaska).
Biology: Nothing is known of immature stages or life history.
Notes: This species is a member of the nivoriundus species group and is one of two species (B. nix and B. pilosus) in this group with long, white pilosity. Males of these two species can be separated by the more numerous denticles behind the tergal hood (33 in B. nix and 19 in B. pilosus). Usually specimens of B. nix are darker in color than specimens of B. pilosus.
Carpenter, F.M. 1935. New Nearctic Mecoptera, with Notes on other Species. Psyche. 42:105-122.