Bodies are slender and with no thoracic or abdominal gills
Hindwing pads nearly parallel to body
Second tarsal segment is much shorter than first
The terga and sterna of abdomen 1-9 seperated by membranous pleural fold
Capniidae is one of the largest families of Plecoptera with approximately 300 species divided between the nearctic, palearctic, and oriental regions. The nymphs are small, but long and slender. They are easily confused with those of Leuctridae, but generally have a groove in the side of the abdomen which extends from segment one to segment nine. In leuctrids this "fold" is not nearly as apparent. The adults emerge during the coldest parts of the winter and are regularly seen walking on snow. In general, capniids are small stoneflies, most about 7 mm in length, although different species might range from 4 mm to more than 25 mm. The nymphs inhabit the hyporheic zone, that is to say the zone of flow beneath the rocks and gravel on the bottom of streams and rivers. The nymphs come close to the substrate surface immediately prior to emergence. As such the nymphs are not always encountered in standard benthic samples, despite their numeric (and presumably ecological) importance. Capniids have many narrowly endemic species, perhaps due to their narrow tolerances for cold environments which trap them in streams on mountain tops or perhaps due to the frequency of winglessness in the group.
Merritt, R W., K W. Cummins, and M B. Berg. An Introduction to the Aquatic Insects of North America. Dubuque, Iowa: Kendall/Hunt Company, 2008