Limnology

Fishflies, Dobsonflies, and Alderflies (Megaloptera)

With approximately 50 North American species, this is a small aquatic order in terms of diversity, but most of its members are quite large. Some Dobsonfly larvae exceed 3 inches in length and the adults are similarly large and impressive, with wingspans of over 4 inches. Larvae are predators, feeding primarily on other insects. Though usually associated with rivers/streams, larvae of some species inhabit ponds and shallower areas of lakes. Megaloptera larvae have distinctive filaments extending sideways from the abdomen. Some water beetles display similar lateral filaments, but lack the paired, hook-bearing prolegs at the end of the abdomen (like fishflies and dobsonflies) and never have the long single filament at the end of the abdomen like alderflies. Pupae and adults are terrestrial. The name Megaloptera refers to how large (megal) the wings (ptera) of the adults look compared to their body.