Adult stoneflies have two pairs of wings which are held together flat and extend beyond the abdomen. The hind wings are much larger than the front and are folded fan-like under the front wing. Stoneflies have long antennae and two long appendages (cerci) at the end of the abdomen. Adults and nymphs (or naiads) have chewing mouthparts.
Nymphs have elongate bodies with long legs and long antennae. They usually have only two tails on the end of the abdomen. The gills of stoneflies are found on the thorax and head. Usually the gills are feathery or branched fleshy extensions often under the base of the legs. They are 1/2 to one inch in length and undergo simple metamorphosis.