This is a small family (Capniidae) with just two genera (Allocapnia and Paracapnia), and 16 species in Ohio. Some species are fairly widespread in Ohio. This family is distinguished by being found in winter, small and with wingpads straight back; the rear wingpads are wider than long and may be or missing in some males (e.g.Allocapnia vivipara, the most common Capniidae). The nymphs are found in fast water in Autumn and the adults come out in late December - February. The nymphal abdomen is slightly swollen in the middle and the rear legs do not extent beyond the end of the abdomen.
As indicated by their common name these flourish in the dead of winter. Nymphs are active in water that measures close to 0 C and the adults are active on snow and sub-zero temperatures. If you are curious as to how they thrive at temperatures that would kill most insects, check out this Scientific American article on the subject: <http://blogs.scientificamerican.com/guest-blog/2011/02/24/winter-stoneflies-sure-are-supercool/>, featuring our own Ohioan, Richard Lee, Professor at Miami University.
Allocapnia vivipara: male (L) and female nymph (R) in each picture.
Allocapnia vivipara (adult male).
