Any of some 1,550 insect species (order Plecoptera) with adults, about 0.
25–2.5 in. (6–60 mm) long, that are generally gray, black, or brown. They have long antennae; weak, chewing mouthparts; and two pairs of membranous wings that, at rest, fold like a fan. The hind wings are generally broader but shorter than the forewings. Despite their well-developed wings, stoneflies are poor fliers. The female drops a mass of up to 6,000 eggs into a stream. Nymphs resemble adults but are wingless and may have external gills; they feed on plants, decaying organic matter, and insects. The nymphal stage lasts one to four years; adults live several weeks.
Stonefly (Plecoptera)
William E. Ferguson