The distribution of the hellgrammite [Corydalus cornutus (Linnaeus)] and the sawcombed fishfly [Nigronia serricornis (Say)] in Michigan was determined as part of an investigation of the biology of these large Megalopterans (Knight and Simmons, 1975a, 1975b). Megalopteran larvae are some of the largest aquatic insects, with a maximum length of approximately 84 mm. They are robust larvae with paired lateral abdominal appendages on segments 1-8 and a pair of anal prolegs bearing two strong hooks. They are fiercely predaceous and generally insectivorous, feeding chiefly on larvae of Simulium, Cheumatopsyche, Hydropsyche and Chironomidae, but eating almost anything they can subdue, including their own kind (Chandler, 1956; Stewart et al., 1973).
Knight, Allen W. and Siegfried, Clifford A.
"The Distribution of Corydalus Cornutus (Linnaeus) and Nigronia Serricornis (Say) (Megaloptera: Corydalidae) in Michigan,"
The Great Lakes Entomologist, vol 10
Available at: https://scholar.valpo.edu/tgle/vol10/iss2/1