Any insect of the family Corydalidae with four net-veined wings, found in North and South America, Asia, Australia, and Africa. The species Corydalus cornutus has a wingspread of about 5 in. (13 cm), and the male has very large jaws (mandibles) of about 1 in. (2.5 cm) or more. Females lay eggs near streams. Larvae live in the streams and, with their strong biting mouthparts, are ferocious predators on other aquatic insects and small invertebrates. Sometimes called hellgrammites or toebiters, they can inflict painful bites on humans; they are eaten by fish, especially bass, and are used as bait by fishermen.