The eastern dobsonfly, Corydalus cornutus, is a large insect in the Corydalidae family. It is found in eastern North America in regions with fast-flowing streams where its aquatic larvae develop. These larvae are known as hellgrammites and are among the top invertebrate predators in the streams in which they live. They are used by anglers as bait.
Dobsonfly eggs are usually laid close to the water's edge on a rock or overhanging foliage and hatch at night one to two weeks later. The newly emerged larvae fall or crawl into the stream and make their way to a fast-flowing section with a stony bottom. These hellgrammites and they hide under stones, catching and eating soft-bodied invertebrates.