Dobsonfly
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| Male Eastern Dobsonfly (Corydalus cornutus) Male Eastern Dobsonfly (Corydalus cornutus)
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Chloronia |
Dobsonfly is the common name for any of the soft-bodied, holometabolous insects comprising the subfamily Corydalinae of the megalopteran family Corydalidae, characterized by four, large, many-veined wings, with many adults noteworthy for their large size and males of some species conspicuous for extremely elongated mandibles. The Eastern dobsonfly (Corydalus cornutus) can reach 12.5 centimeters (five inches) in length and wingpread, and the males have mandibles of 2.5 centimeters (1 inch) or more. The predatory larvae of dobsonflies have strong, biting mouthparts and are known as hellgrammites.
Hellgrammites are well-known to fisherman and aquatic biologist given their large size, endurance as bait, and rather ferocious nature (Contreras-Ramos 1997). They are an important component of the benthic macroinvertebrate fauna of rivers and streams (Contreras-Ramos 1997).
Overview and description
Both male and female dobsonflies can reach lengths up to five inches (12.5 cm), measured from the tips of their pincers to the tips of their four wings, which, when not in use, are folded along the length of their walkingstick-like bodies. Their wingspans can be twice as long as their body length, and the wings themselves are densely lined with intersecting veins. Additionally, dobsonflies have segmented antennae similar to ants and wasps.
Though both male and female dobsonflies have sharp mandibles, those of an adult male dobsonfly are actually so big - up to 1 inch (25 mm) - that they are unable to harm humans, as have such poor leverage that theyre incapable of breaking the skin. They are used exclusively during mating, where males show them off and grasp the females during copulation. Female dobsonflies, however, retain the short, powerful pincers they had as larvae, so they can inflict painful bites, which can draw blood. Nonwithstanding the males' inability to inflict harm, when threatened, both sexes will raise their heads and spread their jaws menacingly. They are not poisonous, but possess an irritating, foul-smelling anal spray as a last-ditch defense.
Their closest relatives are the fishflies. Distributed throughout the Americas, dobsonflies can be rather frightening in their appearance. The males have extremely long mandibles, and the females', while not as long, are nonetheless quite large and intimidating. The most well-known of the numerous species is Corydalus cornutus, the Eastern Dobsonfly. This is a long, dark-colored insect found in North and Central America.
Life cycle
Dobsonflies spend most of their life in the larval stage. Dobsonfly larvae are called hellgrammites, and are familiar to anglers who like to use the chunky larvae as bait. Hellgrammites live under rocks at the bottoms of lakes, streams and rivers, and prey on other insect larvae. After a few years of living and growing underwater, the larvae crawl out onto land and pupate. They stay in their cocoons over the winter and emerge only to mate. Upon emerging, they live for only seven days. While not generally believed to eat during their adult stage, some captive female specimens have been observed with their heads burrowed into blackberries.
Adults can generally be found from late spring into the middle of summer, preferring to remain near bodies of water, particularly the ones where they grew up. Once they emerge as adults they mate, deposit their eggs near the water (often on overhanging vegetation), then die. They are primarily nocturnal, and like most aquatic insects, are commonly attracted to bright lights.
Taxonomy
ReferencesISBN links support NWE through referral fees
- Contreras-Ramos, Atilano. 1997a. Megaloptera. Alderflies, dobsonflies, fishflies. Version 14 October 1997. http://tolweb.org/Megaloptera/8218/1997.10.14 in The Tree of Life Web Project, http://tolweb.org/
Contreras-Ramos, Atilano. 1997b. Corydalinae. Dobsonflies, hellgrammites. Version 15 November 1997. http://tolweb.org/Corydalinae/12999/1997.11.15 in The Tree of Life Web Project, http://tolweb.org/
- Integrated Taxonomic Information System (ITIS). 2004. Corydalinae ITIS Taxonomic Serial No.: 666125. Retrieved May 24, 2008.
External links
- http://www.fcps.k12.va.us/StratfordLandingES/Ecology/mpages/dobsonfly.htm
- http://mbgnet.mobot.org/fresh/slide/dobson.htm
- http://insects.tamu.edu/fieldguide/bimg121.html
- http://tolweb.org/tree?group=Corydalus&contgroup=Corydalinae
- Dobson Fly page at "What's That Bug"
- Hellgrammite page at "What's That Bug"
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