Riffle-habitat
Guides
Corydalus cornutus
Eastern Dobsonfly, Hellgrammite (larval form), Go-devil, Grampus
Corydalus cornutus, the eastern dobsonfly, is among the largest insects in eastern North America, with adults reaching 140 mm in length and wingspans up to 130 mm. The species exhibits pronounced sexual dimorphism: males possess elongated, sickle-shaped mandibles up to 40 mm long used in combat with rivals, while females have shorter, powerful mandibles capable of delivering a painful bite. The aquatic larval stage, known as hellgrammites, are apex invertebrate predators in fast-flowing streams, feeding on other aquatic insects for one to three years before emerging to pupate in terrestrial soil chambers. Adults are short-lived, non-predatory, and primarily nocturnal, attracted to lights near waterways.
Epeorus longimanus
flatheaded mayfly
Epeorus longimanus is a flatheaded mayfly species in the family Heptageniidae. Nymphs inhabit stream riffles and show specific microhabitat preferences, being more abundant in areas with smaller sediment sizes, higher live periphyton biomass, and lower densities of invertebrate predators. The species is distributed across western North America from Alaska through the western United States to southwestern and northern Canada.
Glossosoma
little black caddisflies
Glossosoma is a genus of small caddisflies comprising over 110 described species, commonly known as little black caddisflies. Larvae construct portable dome-shaped cases from mineral particles and occupy the upper surfaces of stones in flowing waters. The genus exhibits multivoltine life histories with varying generation times among species.
Oplonaeschna armata
Riffle Darner
Oplonaeschna armata, commonly known as the riffle darner, is a dragonfly species in the family Aeshnidae. It occurs in Central America and North America. The species has been assessed as Least Concern by the IUCN, with a stable population and no immediate threats identified as of 2017.