37 Plecoptera

Plecoptera

The first orthopteroid order we cover is the Plecoptera (“plektos” = “folded”), or stoneflies. There are about 2500 species worldwide, and about 500 in North America. A few species are quite large, but most are small. Adults are generally poor fliers, with short dispersal distances, and are found near aquatic habitats.

The immature stages are mostly aquatic, and common in cold streams and other habitats. These nymphs/naiads are mostly herbivorous, with a few predatory species; some seem to switch from herbivory to carnivory. Some New Zealand species have terrestrial nymphs, and one species in Lake Tahoe is entirely aquatic, even as an adult. Nymphs are similar to Ephemeroptera nymphs, but have two tarsal claws (not one), cerci but no caudal filament (so, two “tails” not three), and their gills are hair-like tufts that are never found along the abdomen.

Both nymphs and adults are often preserved in ethanol (more delicate species tend to shrivel when air-dried), but robust adults can be pinned. There are several families represented in northern BC.