The
Plecoptera are an
order of
insects, commonly known as
stoneflies. Some 3,500 species are described worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica. Stoneflies are believed to be one of the most primitive groups of
Neoptera, with close relatives identified from the
Carboniferous and Lower
Permian geological periods, while true stoneflies are known from fossils only a bit younger. The modern diversity, however, apparently is of
Mesozoic origin.
