Corydalus cornutus

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Corydalus cornutus
Corydalus cornutus MHNT male.jpg
Mounted male specimen
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Megaloptera
Family: Corydalidae
Genus: Corydalus
Species:
C. cornutus
Binomial name
Corydalus cornutus
Synonyms
  • C. cognatus, Hagen, 1861
  • C. cornutus, Linnaeus, 1758
  • C. crassicornis, McLachlan, 1867
  • C. inamabilis, McLachlan, 1867

The eastern dobsonfly , Corydalus cornutus, is a large insect in the Corydalidae family. It is found in eastern North America in regions with fast-flowing streams where its aquatic larvae develop. These are known as hellgrammites and are among the top invertebrate predators in the streams in which they live. They are used by anglers as bait. [1]

Contents

Distribution

The eastern dobsonfly is found in most of eastern North America. It is usually found near the swift flowing, unpolluted streams in which its larvae develop. [1]

Common names

The origin of the word "dobsonfly" is unclear. John Henry Comstock used the term in reference to this species in his 1897 book Insect Life, [2] but did not explain it. He also mentioned that anglers use the word "hellgrammite" for the aquatic larvae they used as bait, but the origin of this term is also unknown. [3] These common names are still widely used for this and other species of corydalids, and essentially all that is known is that the earliest recorded uses appear to originate in the southern Appalachian region of the US (Kentucky, Tennessee, Virginia, West Virginia), where there were other archaic regional names and variants such as "helgamite", "hojack", "go-devil", and "grampus" (or "crampuss"), all with no definitive source or etymology. [4] The latter name, "grampus", was used in the same region for a large aquatic salamander, the hellbender, that lives in the same habitat. [4]

Description

The eggs are grey and cylindrical, about 1.4 millimetres long and 0.5 millimetres wide. They are laid in groups of about 1,000, stacked in three layers. The pile of eggs is protected by a clear fluid which dries white and is applied by the female with the tip of her abdomen. The egg mass is said to look rather like a bird dropping. [5]

Corydalus cornutus larva, museum specimen Corydalus cornutus larva.jpg
Corydalus cornutus larva, museum specimen

The larvae are light brown with a covering of tiny dark brown microspines. The thorax has three pairs of legs and each segment is covered by a tough, dark-coloured dorsal plate. [6] The first eight abdominal segments have lateral tactile filaments and the first seven have tracheal gills in tufts. [7] The larvae also have spiracles allowing them to breathe on land as well as in the water. At the tip of the abdomen there are two prolegs, each with a dorsal filament and a pair of terminal hooks which enables the larva to anchor itself in fast-flowing water. The mandibles are sclerotised and powerful. [1]

The pupae are orange in colour with dark patches on the upper side of the abdomen and are covered with minute bristles. The developing limbs, wings and antennae project outside the pupal covering. [1]

Eastern Dobsonfly (Corydalus cornutus) female Eastern Dobsonfly (Corydalus cornutus) female.jpg
Eastern Dobsonfly (Corydalus cornutus) female

The adult dobsonfly is a large insect up to 140 millimetres long with a wingspan of up to 125 millimetres. [8] The female has short powerful mandibles of a similar size to those of the larva while the mandibles of the male are sickle-shaped and up to 40 millimetres long, half as long as the body. [1] The antennae are long and segmented and the greyish translucent, many veined wings are often mottled with white dots. When at rest the wings are folded flat over the insect's back and extend beyond the abdomen. [9]

Life cycle

Larva Dobsonfly Corydalus cornutus larvae.jpg
Larva

Dobsonfly eggs are usually laid close to the water's edge on a rock or overhanging foliage and hatch at night one to two weeks later. The newly emerged larvae fall or crawl into the stream and make their way to a fast-flowing section with a stony bottom. They are called hellgrammites and they hide under stones, catching and eating soft-bodied invertebrates. [10] They grow slowly, shedding their skins ten to twelve times and reaching a length of up to ninety millimeters. The larger hellgrammites are fearsome predators with well-developed jaws. After one to three years and when ready to pupate, they emerge from the water and travel up to fifteen metres looking for a suitable location under a rock, log or leaf litter. [11] There may be a mass emergence of hellgrammites within a few days of each other. [12] Each one digs a hole in moist soil and prepares a small, smooth walled chamber, and after a prepupal stage of a few days, sheds their skin and pupates. In some areas the adults emerge in seven to fourteen days [1] but in other areas they overwinter as pupae. [13] On emerging, they dig their way to the surface. They are not thought to feed as adults but spend their time in dense vegetation near streams. They are most active at night and are attracted by lights. They mate and lay their eggs, usually dying within a week. [1]

Related Research Articles

<span class="mw-page-title-main">Pupa</span> Life stage of some insects undergoing transformation

A pupa is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages thereof being egg, larva, pupa, and imago. The processes of entering and completing the pupal stage are controlled by the insect's hormones, especially juvenile hormone, prothoracicotropic hormone, and ecdysone. The act of becoming a pupa is called pupation, and the act of emerging from the pupal case is called eclosion or emergence.

<span class="mw-page-title-main">Aquatic insect</span> Insect that lives in water

Aquatic insects or water insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some diving insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete.

<span class="mw-page-title-main">Megaloptera</span> Order of insects

Megaloptera is an order of insects. It contains the alderflies, dobsonflies and fishflies, and there are about 300 known species.

<span class="mw-page-title-main">Caddisfly</span> Order of caddisflies

The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the basis of the adult mouthparts. Integripalpian larvae construct a portable casing to protect themselves as they move around looking for food, while Annulipalpian larvae make themselves a fixed retreat in which they remain, waiting for food to come to them. The affinities of the small third suborder Spicipalpia are unclear, and molecular analysis suggests it may not be monophyletic. Also called sedge-flies or rail-flies, the adults are small moth-like insects with two pairs of hairy membranous wings. They are closely related to the Lepidoptera which have scales on their wings; the two orders together form the superorder Amphiesmenoptera.

<span class="mw-page-title-main">Dobsonfly</span> Subfamily of insects

Dobsonflies are a subfamily of insects, Corydalinae, part of the Megalopteran family Corydalidae. The larvae 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.

<i>Corydalus</i> Genus of insects

Corydalus is a genus of large flying insects in the Corydalidae family, commonly known as dobsonflies. They are endemic to North, Central and South America and there are about 35 known species. Members of the genus have wing lengths of up to 85 millimetres. They are sexually dimorphic, with the males having large mandibles used to grasp the females during mating while the females have smaller jaws. The larvae are known as hellgrammites and are aquatic predators.

<span class="mw-page-title-main">Chauliodinae</span> Subfamily of insects

Fishflies are members of the subfamily Chauliodinae, belonging to the megalopteran family Corydalidae. They are most easily distinguished from their closest relatives, dobsonflies, by the jaws (mandibles) and antennae. In contrast to the large jaws of dobsonflies, fishfly mandibles are not particularly noticeable or distinctive, and the males have feathery antennae similar to many large moths. Chauliodes pectinicornis, the "summer fishfly", is a well-known species in North America.

<span class="mw-page-title-main">Culicinae</span> Subfamily of flies

The Culicinae are the most extensive subfamily of mosquitoes (Culicidae) and have species in every continent except Antarctica, but are highly concentrated in tropical areas. Mosquitoes are best known as parasites to many vertebrate animals and vectors for disease. They are holometabolous insects, and most species lay their eggs in stagnant water, to benefit their aquatic larval stage.

<span class="mw-page-title-main">Corydalidae</span> Family of insects

The family Corydalidae contains the megalopterous insects known as dobsonflies and fishflies. Making up about one dozen genera, they occur primarily throughout the Northern Hemisphere, both temperate and tropical, and South America.

<span class="mw-page-title-main">Wharf borer</span> Species of beetle

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<i>Sialis lutaria</i> Species of insect

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<span class="mw-page-title-main">European chafer</span> Species of beetle

The European chafer is a beetle of the family Scarabaeidae. Formerly found only in continental Europe, this invasive species is now found at temperate latitudes in North America. The large, white grubs of A. majale feed on the roots of most cool-latitude grasses, both wild and cultivated. This has made the European chafer an enemy of lawns.

<i>Nigronia serricornis</i> Species of insect

Nigronia serricornis has many common names including hellgrammites or fishflies or saw-combed fishflies. The genus Nigronia has one other North American member N. fasciatus and South American which lives in much of the same territory and is quite similar in all regards. They are holometabolous insects with an aquatic larval stage. N. serricornis is a common inhabitant of woodland streams in North America and they are often the largest insect predator found in 2nd and 3rd order streams. The larvae are a sit-and -wait ambush predators that feed on a large variety of invertebrates. Studies have shown that N. serricornis has a varying diet throughout the seasons.

<i>Archichauliodes diversus</i> Species of insect

Archichauliodes diversus is an insect in the subfamily Chauliodinae - the fishflies, though it is often referred to as the New Zealand dobsonfly, despite not being a true dobsonfly. In its larval form it is commonly known by the name toe-biter, and its Māori name is puene. The species is native to New Zealand. Although there are many other species of fishfly in other parts of the world, Archichauliodes diversus is the only species of fishfly in New Zealand.

<i>Platyneuromus</i> Genus of insects

Platyneuromus is a genus of dobsonflies in the family Corydalidae. They are found in Mexico and Central America.

<i>Acanthacorydalis fruhstorferi</i> Species of insect

Acanthacorydalis fruhstorferi is a species of dobsonfly native to Vietnam and China. It holds the title of largest aquatic insect by wingspan according to the Guinness Book of World Records at 21.6 cm. The title formerly belonged to the Brazilian damselfly Microstigma rotundatum.

<i>Chloronia</i> Genus of insects

Chloronia is a genus of dobsonflies in the family Corydalidae.

<i>Protohermes</i>

Protohermes is a genus of dobsonflies in the family Corydalidae. Protohermes is the most specious and widely distributed genus within Megaloptera, but up to 85% of species are restricted to small endemic areas in Asia. This endemism may be a result of an association with high elevation and high slope streams in Northern Vietnam and China.

<i>Parachauliodes</i>

Parachauliodes is a genus of fishfly in the family Corydalidae. They are present throughout Eastern Asia, likely originating on the Korean peninsula before dispersing to the Japanese archipelago 15 mya.

<i>Neurhermes</i>

Neurhermes is a genus of dobsonflies in the family Corydalidae.

References

  1. 1 2 3 4 5 6 7 Featured Creatures
  2. Comstock, John Henry (1897). Insect Life. Cornell University Library. Online.
  3. Turpin, T. Dobsonflies Look Vicious. Purdue Agriculture News Columns. Purdue Extension. August 8, 2013.
  4. 1 2 Dictionary of American Regional English: "grampus"
  5. Baker, J. R. and H. H. Neunzig. 1968. The egg masses, eggs and first-instar larvae of the eastern North American Corydalidae. Annals of the Entomological Society of America 61: 1181-87.
  6. Neunzig, H. H. and J. R. Baker. Order Megaloptera. 1991. In: Stehr, F. W., editor. Immature Insects, Vol. 2. Kendall/Hunt Publishing Company. Dubuque, Iowa. pp. 112-22.
  7. Barclay, A., et al. 2005. Tracheal gills of the dobsonfly larvae, or hellgrammite Corydalus cornutus L. (Megaloptera: Corydalidae). Journal of the Kansas Entomological Society 78: 181-85.
  8. BugGuide
  9. "Field Guide to Texas Insects". Archived from the original on 2010-12-05. Retrieved 2011-01-05.
  10. McCafferty, W. P. and A. V. Provonsha. 1983. Aquatic Entomology: The Fisherman's and Ecologist's Illustrated Guide to Insects and Their Relatives. Jones and Bartlett Publishers, Inc. Portola Valley, California. 448 pp.
  11. Mangan, B. P. 1994. Pupation ecology of the dobsonfly Corydalus cornutus (Corydalidae: Megaloptera) along a large river. Journal of Freshwater Ecology 9: 57-62.
  12. Voshell, J. R. 2002. A Guide to Common Freshwater Invertebrates of North America. The McDonald & Woodward Publishing Company. Blacksburg, Virginia. 442 pp.
  13. Eastern Dobsonfly. Archived 2010-09-25 at the Wayback Machine Fairfax County Public Schools.