The Plecoptera are an order of insects, commonly known as stoneflies. There are approximately 3,500 species found worldwide, except in Antarctica. Almost all species of stoneflies develop as nymphs in clean, moving water and are intolerant of water pollution. Their presence in a stream or still water is therefore a good indicator of excellent water quality. Once hatched from the eggs, stonefly nymphs usually complete their development within a year. Some larger species may spend two to three years as nymphs before crawling out of the water as adults. A good example is our Golden Stone (Hesperoperla pacifica).
Once they emerge from the water, adult stoneflies will usually spend their lives within close proximity to the water’s edge. Unlike the outstretched wings of dragonflies and damselflies, stoneflies fold their wings neatly against their backs when at rest and are generally not strong fliers.