Home | Stonefly Nymph Key | Species List | Bibliography | Glossary

Stoneflies - Plecoptera: Nemouridae of Gunnison County, Colorado
Nymph key to Genera

Updated 17 August 2008
1a. Cervical gills present
1b. Cervical gills absent
2a. Cervical gills with 5 or more branches. Femora plain, no setae.
2b. Four simple cervical gills or gills with 4 or fewer branches. Legs with band of setae around femora of legs.

The setae on the backs of their legs is visible on very small nymphs and on the animal at the right.

3a. Cervical gills branch from a basal trunk. Most of gills are about the same length with a few shorter gills on the outside of the neck. Gills do not branch secondarily.
3b. Some cervical gills branch midway out their length. Gills branch palmately from base. Gills vary in length.

(Some gills have a Y-shape)

4a. A fringe of long hairs on the outer margin of the foretibia.
4b. No fringe on foretibia although a few long hairs may be present.

Good Links

Key to Nemouridae Females of Gunnison County
Key to Nemouridae Males of Gunnison County


Baumann,RW; Gaufin,AR; Surdick,RF 1977 The stoneflies (Plecoptera) of the Rocky Mountains. Memoirs of the American Entomological Society 31, 1-208.

Stewart,KW and Stark,BP 2002 Nymphs of North American Stonefly Genera. 2nd edition The Caddis Press, Columbus, Ohio. 510 pages.

Ward,JV, Kondratieff,BC and Zuellig,RE 2002 An Illustrated Guide to the Mountain Stream Insects of Colorado. 2nd ed. University Press of Colorado, Boulder, Colorado. 219 pages.

Brown, Wendy S. 2004 Plecoptera or Stoneflies of Gunnison County, Colorado