Stoneflies: Plecoptera

Physical characteristics: The giant salmonfly is a large stonefly measuring 1.18 to 1.97 inches (30 to 50 millimeters) in length, with a wingspan of 2.25 to 3.25 inches (58 to 84 millimeters). They are dark brown, with a reddish line down the middle of their midsection. The larvae have branched gills under the first two abdominal segments. These gills are reduced to small stubs in the adults.

Geographic range: The giant salmonfly is widespread in western North America.

Habitat: Adults and larvae are associated with fast-moving mountain streams.

The giant salmonfly is an important food source for trout. Both the larvae and adults are used as models by fly fishermen to create artificial lures. (Illustration by Jonathan Higgins. Reproduced by permission.)

Diet: The larvae feed on algae and shred plant materials. The adults do not feed.

Behavior and reproduction: Adult males and females emerge in spring and gather along streams and rivers on vegetation for drumming and mating. Males produce heavy six-beat signals, and females answer with similar signals. The larvae require two to three years to reach adulthood.

Giant salmonflies and people: The giant salmonfly is an important food source for trout. Both the larvae and adults are used as models by fly fishermen to create artificial lures.

Conservation status: This species is not endangered or threatened. ∎