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
Size
adult: body 48-60 mm
(1), 100-140 mm to wingtips (wingspan to 125 mm); larva up to 70 mm
(1)Identification
Widespread eastern species with pale markings on the head and with the many pale spots in the wings not margined by a dark ring. Males have spectacular mandibles. Compare
Chauliodes, which has a different shape to thorax and head, lacks enlarged mandibles.
♀
♂
Range
Eastern North America (only species in east)
Habitat
Larvae in fast-flowing streams; adults come to lights
Food
Larvae are 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"
(2) as is the origin of
dobsonfly. Sources (e.g.,
(3)) 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
(4):
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.
