Dobsonfly larvae

Corydalus cornutus is a dobsonfly belonging to the family Corydalidae and Order Megaloptera. The genus Corydalus contains 35 species restricted to the western hemisphere. Members of the genus have wing lengths ranging in size from 35-85 mm. They are sexually dimorphic, with males having large sickle-shaped mandibles. Corydalus cornutus is the type species of the genus and is widely distributed throughout the eastern United States.

Eggs are laid on rocks or leaves above fast-flowing streams and may look like bird feces. The larvae, referred to as hellgrammites, hatch out and fall into the water. They are predators whose diet includes small insects, fish, and tadpoles. Hellgrammites are elongate, dull-colored larvae with gill filaments and feathery gill clusters along the sides of the abdomen. They have two hooks on the end of the abdomen. Larvae do best in well-oxygenated, high quality water. Larvae can take 2-3 years to develop, before they leave the water and pupate in an earthen chamber on the shoreline. Larvae are often favored as fish bait. They do have powerful mandibles and can inflict a fierce bite.

The adults are most often noticed when attracted to lights at night. They probably do not feed, and only live a week or so as they search for mates.