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.
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The name dobsonfly refers to insects of the subfamily Corydalinae, part of the megalopteran family Corydalidae. The Dobsonfly is also referred to as "The King Bug," because of its kingly features and intimidating tusks. Their closest relatives are the fishflies. Distributed throughout the Americas, dobsonflies can be rather frightening in their appearance. The males have extremely long mandibles, and the females', while not as long, are nonetheless quite large and intimidating. The most well-known of the numerous species is Corydalus cornutus, the Eastern Dobsonfly. This is a long, dark-colored insect found in North and Central America.
Both male and female dobsonflies can reach lengths up to five inches (12.5 cm), measured from the tips of their pincers to the tips of their four wings, which, when not in use, are folded along the length of their walkingstick-like bodies. Their wingspans can be twice as long as their body length, and the wings themselves are densely lined with intersecting veins. Additionally, dobsonflies have segmented antennae similar to ants and wasps.
Though both male and female dobsonflies have sharp mandibles, those of an adult male dobsonfly are actually so big - up to 1 inch (25 mm) - that they are unable to harm humans, as have such poor leverage that they are incapable of breaking the skin. They are used exclusively during mating, where males show them off and grasp the females during copulation. Female dobsonflies, however, retain the short, powerful pincers they had as larvae, so they can inflict painful bites, which can draw blood. Nonwithstanding the males' inability to inflict harm, when threatened both sexes will raise their heads and spread their jaws menacingly. They are not poisonous, but possess an irritating, foul-smelling anal spray as a last-ditch defense.
Dobsonflies spend most of their life in the larval stage. Dobsonfly larvae are called hellgrammites, and are familiar to anglers who like to use the large larvae as bait. Hellgrammites live under rocks at the bottoms of lakes, streams and rivers, and prey on other insect larvae. After a few years of living and growing underwater, the larvae crawl out onto land and pupate. They stay in their cocoons over the winter and emerge only to mate. Upon emerging, they live for only seven days. While not generally believed to eat during their adult stage, some captive female specimens have been observed with their heads burrowed into blackberries.
Adults can generally be found from late spring into the middle of summer, preferring to remain near bodies of water, particularly the ones where they grew up. Once they emerge as adults they mate, deposit their eggs near the water (often on overhanging vegetation), then die. They are primarily nocturnal, and like most aquatic insects, are commonly attracted to bright lights.