EPOW - Ecology Picture of the Week

Stonefly Larva

Common Stonefly (cf. Golden Stone, Hesperoperla pacifica), Family Perlidae
Middle Fork John Day River, Oregon USA

Explanation:  Along the banks of the Middle Fork of the John Day River in eastern Oregon, USA, I happened upon this bit of insectan armor -- the larva of a common stonefly.  This is a member of the arthropod family Perlidae, that globally boasts almost 1000 species among 52 genera, with some 84 species in North America.  

This individual is in its larval stage of development, later to emerge with wings in the adult stage.  It might be a member of the Golden Stone species, with a life cycle running two to three years.  And, in general, common stoneflies can be confused with some of the similarly-appearing mayflies, particularly the flathead mayfly. 

Common stoneflies occupy streams and rivers, and feed on a wide variety of other invertebrates.