Dobsonflies are a subfamily of insects, Corydalinae, part of the Megalopteran family Corydalidae. The larvae (commonly called hellgrammites) are aquatic, living in streams, and the adults are often found along streams as well. The nine genera of dobsonflies are distributed in the Americas, Asia, and South Africa. Etymology The origin of the word "dobsonfly" is unclear. John Henry Comstock used the term in reference to these insects in his 1897 book Insect Life, but did not explain it. He also mentioned that anglers used the word "hellgrammite" for the aquatic larvae they used as bait, but the origin of this term is also unknown. Description Adult dobsonflies are some of the largest non-Lepidopteran insects of temperate zones such as the United States and Canada, with a wingspan of up to in some species of Corydalus. The Asian Acanthacorydalis fruhstorferi can have a wingspan of up to , making it the largest dobsonfly and the largest aquatic insect in the world by this measurement. The wings vary from a grayish to translucent shade, depending on the species, and the anal region of the hindwing is wide and folded at rest. Despite the large wings, adults are weak, fluttery fliers. The body is soft and coloration varies from yellow to dark shades of brown. The body typically does not surpass in length, although the largest Asian Acanthacorydalis may reach . Adult males of many—but not all—species are easily recognized by their long, curving mandibles. Examples of species with large-mandibled males include the genera Acanthacorydalis, Corydalus and Platyneuromus, while in Neoneuromus, Nevromus, Neurhermes and Protohermes the sexes are similar. In Corydalus cornutus, a particularly long-mandibled species, these can reach up to in length and are used in competition for females. It is possible that the mandibles may have been selected as secondary sex characteristics used by females to evaluate males during courtship. Males cannot use these mandibles to bite because they are too long; on the other hand, females have short, heavily sclerotized mandibles which enable them to deliver powerful bites when threatened. Males of many species will also produce "nuptial gifts" in the form of packages of nutrient-rich spermatophores that are eaten by the female partner after mating. This has been shown to be correlated to mandible size; in species where the males have large mandibles the "nuptial gift" is small or absent, while it is large in species where males lack