Eastern Dobsonfly

Corydalus cornutus is the eastern dobsonfly, one of about 30 species in family Corydalidae and order Megaloptera — a primitive holometabolous insect lineage that diverged from the rest of the holometabolous radiation in the Permian (~280 million years ago). Male dobsonflies are unmistakable: they carry curved sickle-shaped mandibles up to 4 cm long, longer than the rest of the head. The mandibles are too long and too lightly muscled to actually bite — they are used purely in male-male competition for mates, where rivals lock jaws and try to flip each other off perches. Females have shorter, more functional mandibles and CAN deliver a sharp painful bite if handled. Adults are nocturnal, drawn to lights, and live only 3-7 days, during which they do not feed (the adults survive entirely on stored larval reserves). The aquatic larva — the famous 'hellgrammite' of Appalachian fishing tradition — is a different kind of animal entirely. Hellgrammites are fierce 8 cm predators with strong sickle-jaws and a pair of hooked anal prolegs that anchor them to rocks in fast streams. They live 2-3 years underwater, hunting smaller insects and any small fish they can grab. They are prized as smallmouth bass and trout bait throughout the eastern US. When the larva is mature, she crawls out of the water and pupates under stones or logs near shore.