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Montana Field Guide

Montana Field Guides

Ice Snowfly - Bolshecapnia spenceri

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Native Species

Global Rank: G3
State Rank: SNR
(see State Rank Reason below)

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Known from approximately two dozen occurrences in the Canadian and northern Rockies of Alberta, British Columbia, Montana (Flathead Co., Glacier Co.).
General Description
Species within the Capniidae are small winter stoneflies. This family is one of the largest families in the order Plecoptera, containing some 300 species distributed throughout the Holarctic region, 25 species occur in Montana. As their name implies these species are generally cold-water stenotherms and hatch in late-winter through early spring. The adults emerging in the winter are often found walking around on the snow. Their closest relatives are the rolled-winged stoneflies (Leuctridae). Many species are endemic to small ranges, perhaps due to the family's tendency to evolve tolerance for cold (isolating populations in mountain valleys) and winglessness (inhibiting dispersal).

Range Comments
This species occurs in streams and lakes. A large population occurs in Iceberg Lake, Glacier National Park, Montana. Gaufin et al. (1972) cite Montana distribution as Iceberg Lake in Glacier National Park. Jacobus et al. (2006) report it from Glacier National Park only on the east side of the Continental Divide in western Montana.

This species occurs at or near high mountain lakes and their associated creeks (Stewart and Oswood, 2006).

Food Habits
Merritt and Cummins (1996) report that members of this family are trophically shredder-detritivores; eating large particulate organic materials such as detritus, leaves and plants.

Cold-water stenotherms and shredder functional feeding group.

Reproductive Characteristics
Adults have been collected in Iceberg Lake, Montana, only in July and early August (Gaufin et al., 1972).

Threats or Limiting Factors
Specific threats to MT populations of Bolshecapnia spenceri have not been identified. In general, stonefly populations are affected by changes to aquatic habitat such as alteration of flow patterns, streambed substrate, thermal characteristics, and water quality. Alteration and degradation of aquatic habitat and dimisnished snowpack is a primary concern for MT populations.

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Citation for data on this website:
Ice Snowfly — Bolshecapnia spenceri.  Montana Field Guide.  .  Retrieved on , from