Vol. 3: Insects |
Order: Megaloptera |
Species accounts
Eastern dobsonfly
Corydalus cornutus
FAMILY
Corydalidae (Corydalinae)
TAXONOMY
Hemerobius cornutus Linneus, 1758, Pennsylvania.
OTHER COMMON NAMES
English: Hellgrammite, toebiter, bass bait (larva); French: Grande mouche Dobson (adult).
PHYSICAL CHARACTERISTICS
The adult is 2 in (50 mm) long, with a wingspan up to 5 in (125 mm), and the larva is 2.6 in (65 mm) long. The head is almost circular and the prothorax square and slightly narrower than the head. The wings are translucent gray with dark veins and cells with white spots. The mandibles of the male are as long as half of the body length, curved and tapering to the tips and held crossing each other. The mandibles of the female are shorter.
DISTRIBUTION
Occur east of the Rocky Mountains in the United States and Canada.
HABITAT
Larvae live in fast-flowing water.
BEHAVIOR
Adults are nocturnal and secretive and are seldom seen during the daytime, when they hide under leaves in the canopy of trees. Larvae have been seen swimming forward or backward in a snakelike fashion, but they usually crawl.
FEEDING ECOLOGY AND DIET
Adults do not feed; larvae consume other insects and small invertebrates.
REPRODUCTIVE BIOLOGY
Mating behavior is stereotypical; males flutter their wings, display genital appendages, and fight over females. Rounded masses containing 100–1,000 or more eggs are laid on rocks, branches, and objects close to the water. Each mass is coated with a whitish secretion. Larvae drop into the water or crawl to reach feeding grounds. After two or three years, they crawl out of the water and prepare pupal chambers under stones or logs, where they overwinter. Adults emerge in early summer.
CONSERVATION STATUS
Not threatened.
Sialis lutaria
Corydalus cornutus
Archichauliodes diversus
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Order: Megaloptera
SIGNIFICANCE TO HUMANS
Fishermen use dobsonfly larvae, called hellgrammites, as bait for trout, largemouth bass, catfish, and other fishes. Hellgrammites also help control populations of pest aquatic insects, such as the Asian tiger mosquito.
Black creeper (larva), Dobsonfly (adult)
Archichauliodes diversus
FAMILY
Corydalidae (Chauliodinae)
TAXONOMY
Chauliodes diversus Walker, 1853, New Zealand.
OTHER COMMON NAMES
English: Toebiter, black fellow (larva).
PHYSICAL CHARACTERISTICS
Larvae have a long, thin, gray body up to 2 in (50 mm) long and a subtriangular jet-black head. Adults are about 2–3 in (50–75 mm) long with large, clear wings with a 2–3.2 in (50–80 mm) wingspan.
DISTRIBUTION
New Zealand.
HABITAT
Stony streams and rivers. Older larvae are found beneath dry stones close to the water’s edge.
BEHAVIOR
Larvae cling to the stream bottom in all but the strongest flows and become dislodged only with flooding. Adults fly in a slow, clumsy manner and only for short distances at low heights over streams.
FEEDING ECOLOGY AND DIET
Larvae feed on mayfly larvae; adults do not feed.
REPRODUCTIVE BIOLOGY
Larvae take from 18 months to three years to reach full size. Adults emerge in summer and live for only six to 10 days. Eggs that are laid late in the season undergo obligate diapause (suspension of development, which starts again once climatic conditions become more favorable).
CONSERVATION STATUS
Not threatened.
Vol. 3: Insects
SIGNIFICANCE TO HUMANS
Larvae often are used by anglers as trout bait.
Alderfly
Sialis lutaria
FAMILY
Sialidae
TAXONOMY
Hemerobius lutaria Linnaeus, 1758, Europe.
OTHER COMMON NAMES
French: Mouche du Saule; German: Gemeine Wasserflorfliege; Danish: Dovenflue.
PHYSICAL CHARACTERISTICS
Adults are 0.52–0.72 in (13–18 mm) in length and blackishbrown in color.
DISTRIBUTION
Occurs in Europe and into Russia.
HABITAT
Larvae inhabit the depths of still waters and muddy backwaters of rivers.
BEHAVIOR
During spring and early summer adults are found on plants near the water; they fly only when it is sunny and warm.
FEEDING ECOLOGY AND DIET
Larvae feed on worms, insect larvae, and other small freshwater animals. Adults occasionally take nectar from flowers with easily accessible nectaries.
REPRODUCTIVE BIOLOGY
After mating, the female deposits dark gray eggs on leaves of littoral vegetation and then cleans the newly laid eggs. Larvae crawl into the water and scurry to the bottom, where they tunnel in the silt. After two winters the larva leaves the water and pupates for two weeks. The greatest numbers of adults are seen on the wing from May through mid-June.
CONSERVATION STATUS
Not threatened.
SIGNIFICANCE TO HUMANS
They are bioindicators in water quality assessment.
Resources
Books
Brigham, W. U. “Megaloptera.” In Aquatic Insects and Oligochaetes of North and South Carolina, edited by A. R. Brigham, W. U. Brigham, and A. Gnilka. Mahomet, IL: Midwest Aquatic Enterprises, 1982.
Chandler, H. P. “Megaloptera.” In Aquatic Insects of California, edited by R. L. Usinger. Berkeley: University of California Press, 1956.
Contreras-Ramos, A. Systematics of the Dobsonfly Genus Corydalus Latreille (Megaloptera: Corydalidae). Thomas Say
Monographs. Lanham, MD: Entomological Society of
America, 1998.
Evans, E. D., and H. H. Neunzig. “Megaloptera and Aquatic Neuroptera.” In An Introduction to Aquatic Insects of North America, edited by R. W. Merritt and K. W. Cummins. 3rd. edition. Dubuque, IA: Kendall/Hunt Publishing Company, 1996.
Henry, C. S., N. D. Penny, and P. A. Adams. “The Neuropteroid Orders of Central America (Neuroptera and Megaloptera).” In Insects of Panama and Mesoamerica, edited
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Vol. 3: Insects
Resources
by D. Quintero and A. Aiello. Oxford: Oxford University Press, 1992.
Penny, N. D. “Neuroptera.” In Aquatic Biota of Tropical South America. Part 1, Arthropoda, edited by S. B. Hurlbert, G. Rodríguez, and N. Dias dos Santos. San Diego: San Diego State University, 1981.
—. “Neuroptera.” In Aquatic Biota of Mexico, Central America and the West Indies, edited by S. B. Hurlbert and A. Villalobos-Figueroa. San Diego: San Diego State University, 1982.
Periodicals
Contreras-Ramos, A. “Mating Behavior of Platyneuromus
(Megaloptera: Corydalidae), with Life History Notes on
Order: Megaloptera
Dobsonflies from Mexico and Costa Rica.” Entomological News 110 (1999): 125–135.
Davis, K. C. “Sialididae of North and South America.” New York State Museum Bulletin 68 (1903): 442–486, 499.
Stewart, K. W., G. P. Friday, and R. E. Rhame. “Food Habits of Hellgrammite Larvae, Corydalus cornutus (Megaloptera: Corydalidae), in the Brazos River, Texas.”
Annals of the Entomological Society of America 66 (1973): 959–963.
Natalia von Ellenrieder, PhD
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