This order of insects contains the alderflies, dobsonflies and fishflies, with about 300 known species. Megaloptera are relatively unknown insects across much of their range, due to the adults’ short lives, the aquatic larvae’s often-high tolerance of pollution and are generally nocturnal. The new world dobsonflies however are rather well known, as their males have tusk-like mandibles. These, while formidable in appearance, are relatively harmless to humans and other animals, serving mainly to impress females and also used to hold females during mating. Some male dobsonflies also use these to spar with each other in courtship displays, trying to flip each other over with their long mandibles. Dobsonfly larvae, commonly called hellgrammites, are often used for angling bait in North America.
The Megaloptera were formerly considered part of a group then called Neuroptera, together with lacewings and snakeflies, but these are now generally considered to be separate orders. The former Neuroptera, particularly the lacewing group, are nonetheless very closely related to each other, and the new name for this group is Neuropterida.