Boreus nivoriundus Fitch, 1847
Diagnosis: Body color brown; length: male, pinned = 2.3 – 3.6 mm; female, pinned = 3.5 – 4.4 mm; male, in alcohol = 4.9 – 5.4 mm; female, in alcohol = 4.9 – 5.8 mm. Ratio of length of maxilla-labial complex to rostrum = .90. Anterior and posterior margins of pronotum with 4 to 6 bristles; meso- and metanota each with 2 bristles. Male forewings pale brown, evenly tapered to apex, with 16-18 mesal spines and 14 lateral spines. Hindwings with 16 spines. Female forewings oval, covering hindwings. Male 8th tergum and sternum unfused; 9th tergum and sternum also unfused. Hood of 9th tergum very small, only about 1/6 width of tergum, without medial, longitudinal ridge. Apex of male 9th sternum broadly rounded.
Distribution – Geographical: Adults of this species have been collected over most of the New England states and as far south as Newfound Gap in the Great Smoky Mountains of Tennesee and as far west as Ohio.
Distribution – Temporal: Adults have been collected from 19 November until 28 March from sea level in the north to 5,000 feet in the southern part of the range.
Ecology: This species appears to inhabit terrestrial mosses in cool, moist habitats.
Biology: Nothing is known of immature stages or life cycle.
Notes: This species can be separated from all other species of Boreus, except B. elegans, by the combination of bristles on the pronotum, short abdominal pilosity, and rounded apex of the male 9th sternum. Boreus nivoriundus is smaller than B. elegans, a darker brown color, fewer setae on the rostrum, and smaller denticles under the tergal hood.
The name nivoriundus comes from the Latin word nivarius, meaning snow or snowy and refers to the winter activity of adults.
Fitch, A. 1847. Winter Insects of eastern New York. American Journal of Agricultural Science, 5:274-284.