American Salmonfly (Pteronarcys dorsata)
Detailing the identifying qualities of the American Salmonfly, including physical features and territorial reach.
Updated: 1/31/2018; Authored By Staff Writer; Content ©www.InsectIdentification.org
The large and unassuming American Salmonfly is a water-loving, ecologically sensitive insect that occasionally plays opossum.
American Salmonflies are the largest North American stonefly and are most active from late spring to late summer. Like other members of the Stonefly family, the American Salmonfly is a useful bio-indicator. The aquatic larvae of the American Salmonfly live underwater during these early life stages and they are extremely sensitive to pollution. If the water is laced with chemicals, the larvae will die. Hence, the sight of many adults means the water source and the ecosystem it supports is healthy and clean. For fishermen in such waters, the sight of American Salmonflies is most welcome.
Adults do not eat and have short life spans of less than a month. They are long and slender with dark wings that close tightly around their bodies. Their black eyes are bulge out of the sides of their head. A dark pronotum ('neck collar') is bordered in bright orange at both ends and a fading orange line that almost connects both ends. Long, black antennae and legs resemble those of beetles. They rest on rocks, reeds, and branches near or above water, waiting for opportunities to reproduce. If adults are threatened, they can release a chemical irritant from their legs in hopes of dissuading an attacker. If that fails, they may play dead.
Females drop fertilized eggs into the water. There, they hatch and develop into larvae. Their diet consists of algae and other rotting plant matter underwater. They are an important food source for fish living in the same waters. Anglers, especially fly fishers, use living larvae as well as manufactured imitations as fish bait. Where there are Salmonflies, there are fish, and consequently, fishermen. Larvae look like little crustaceans, not flying insects. After several rounds of molting and growing, they eventually leave the water where they mature into winged adults, shedding their exuviae, or exoskeletons. These empty 'shells' are abandoned not far from the water's edge.