Montana Field Guide

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).

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.

Specific threats to MT populations of Bolshecapnia milami 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.