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Species Corydalus cornutus - Eastern Dobsonfly

found in New England - Corydalus cornutus Dobson Fly - Corydalus cornutus - female Large Mystery Bug #2 - Corydalus cornutus - male Giant Lacewing - Corydalus cornutus - male strange bug - Corydalus cornutus Corydalus cornutus - Eastern Dobson Fly - Corydalus cornutus - female Eastern Dobsonfly - Corydalus cornutus - female weird bug in NC - Corydalus cornutus
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Megaloptera (Alderflies, Dobsonflies, and Fishflies)
Family Corydalidae (Dobsonflies and Fishflies)
Subfamily Corydalinae
Genus Corydalus (Dobsonflies)
Species cornutus (Eastern Dobsonfly)
Other Common Names
Hellgrammite (larva), Dobson (larva, see below), Hellgrammite Fly, Horned Corydalus, Grampus (from Krampus, a mythological monster), Go-devil
Synonyms and other taxonomic changes
Corydalus crassicornis, Corydalus inamabilis
Explanation of Names
Corydalus cornutus (Linnaeus 1758)
cornutus = 'horned'
common names discussed below
Size
adult: body 48-60 mm(1), 100-140 mm to wingtips (wingspan to 125 mm); larva up to 70 mm(1)
Identification
widespread species in Eastern North America. Males have spectacular mandibles. Compare Chauliodes, which has a different shape to thorax and head, lacks enlarged mandibles.
Arnett (2) mentions the white spots in many of the wing cells and the large mandibles as identifying characteristics for this genus.

Range
Eastern North America (only species in east)
Habitat
Larvae in fast-flowing streams; adults come to lights
Season
Late spring-early fall
Food
Larvae predatory; adults do not feed
Life Cycle
Eggs laid in masses of 100-1,000 on rocks (or vegetation) above the waterline. Larvae drop or crawl into water. Larva develops for 2-3 years, then crawls out of water, builds pupal cell under log, rock, etc. and overwinters. Adults emerge spring to summer.
Remarks
The huge male mandibles are used to hold females during mating. The females, with much shorter jaws, can bite more effectively. Adults do not feed but may use mandibles for self-defense.
Etymology of hellgrammite is "obscure"(3) as is the origin of dobsonfly. Sources (e.g.,(4)) note that both terms were bestowed by fisherman who used the larvae as bait. Both terms were used in The Standard Natural History (1884-1885, vol. II: 156): "At this [larval] period [...] they are much sought after as fish-bait [...] and they are called by fishermen 'crawlers,' 'dobsons,' and sometimes... 'hellgrammites.' (Walsh & Riley 1861) [Speculation: Hellgrammite might be a compound of hell + grim (fierce, cruel); The Online Etymology Dictionary notes: "...It (grim, Old English grimma) also had a verb form in O.E. (Old English), grimman (class III strong verb; past tense gramm, p.p. grummen). O.E. also had a noun, grima "goblin, specter," perhaps also a proper name or attribute-name of a god, hence its appearance as an element in place names. As a noun meaning "a form of bogey or haunting spirit," first recorded 1628. The Old English grimm/gramm are certainly suggestive. A folk etymology origin (from a Native American word?) certainly seems possible as well.
Speculation(2). The word "dobson" sounds like a folk etymology for another word for the larva, possibly of Native American origin. Another possibility is that it is a reference to another aquatic creature, the dolphin (from French daulphin). Note that originally "dobson" was a term for the larva.
See Also
Three other species have limited distribution in our area and are treated as synonyms of C. cornutus in(5): C. luteus s. TX, C. texanus sw. US, C. bidenticulatus AZ
Print References
Bowles D.E. (1990) Life history and variability of secondary production estimates for Corydalus cornutus (Megaloptera: Corydalidae) in an Ozark stream. J. Agric. Entomol. 7: 61-70.
Milne(6)
Swan and Papp(7)
Internet References
Grampus and go-devil (MacRae 2012)
Works Cited
1.A guide to the Megaloptera and aquatic Neuroptera of Florida
Rasmussen A.K., Pescador M.L. 2002. Florida Dept of Environmental Protection, Div. Water Resource Management. Tallahassee. iii+45 pp.
2.American Insects: A Handbook of the Insects of America North of Mexico
Ross H. Arnett. 2000. CRC Press.
3.A Dictionary of Entomology
George Gordh, David H. Headrick. 2003. CABI Publishing.
4.The Century Dictionary: an encyclopedic lexicon of the English language
5.Species catalog of the Neuroptera, Megaloptera, and Raphidioptera of America North of Mexico
Penny N.D., Adams P.A., Stange L.A. 1997. Proc. Calif. Acad. Sci. 50: 39-114.
6.National Audubon Society Field Guide to Insects and Spiders
Lorus and Margery Milne. 1980. Knopf.
7.The Common Insects of North America
Lester A. Swan, Charles S. Papp. 1972. Harper & Row.
8.Guide to Insects of Quebec