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Aeshnidae
Phylum Arthropoda
Class Insecta
Order Odonata
Suborder Anisoptera
Family Aeshnidae
Common Name Darner
 
Distinguishing Characteristics
  • Elongated body (1)
  • Flat prementum (1)
  • Antennae are thin with six to seven segments (1)
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Ecology
Habitat
     Aeshnidae are distributed throughout North America in aquatic arid climates (2). Some species can be found in low flowing streams and riffles of rivers. The majority of Aeshnidae species are found in lentic habitats, primarily in marshes, littoral lake environments, and ponds with high vegetation (1). Dead and decaying debris, and submerged logs are favored for shelter and protection from predation (2).

Life History
     The life cycle takes two to four years to complete (1). The species Anax junius, has a shorter developmental stage, reaching adulthood more rapidly compared to other Aeshnidae species. The shortened larval stage is due to the migration the species participates in for the wintering months in North America. Migration south in autumn and returning north in the spring to reproduce (1).
     The larvae of Anax imperator have black and white bands around the body. Adapted for camouflage for those living near the surface. Aeshna grandis take up to 3 years to reach maturity. The banding pattern is present for the first 2 years of development. A characteristic unique to the species since other species, such as the univoltine Ae. mixta lose the banding pattern after the second instar of larval development (3).
     Influenced by air and water temperature cycles, adult emergence can occur any time from late May to early July depending on the species (4). Larvae emerge from the water at dusk and crawl up an object positioned vertically to dry off. Once dry the larvae rapidly moves their abdomen back and forth in order to break the cuticle casing around the thorax. The cuticle breaks down for the final stage of molting and maturation into an adult with wings (3). The flight season typically lasts a month, during this time reproduction occurs. Most species are univoltine while others, such as Boyeria vinosa have semivoltine reproductive cycles (2).

Feeding Behavior
     Aeshnidae are predacious organisms and feed primarily on invertebrates and small vertebrates (1).
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Bibliography

(1) Thorp, J.H. and A.P. Covich. 2010. Ecology and Classification of North American Freshwater Invertebrates, pp. 587-657. Elsevier Inc. Boston.

(2) Burcher, C.L. and L.A. Smock. 2002. Habitat Distribution, Dietary Composition and Life History Characteristics of Odonate Nymphs in a Blackwater Coastal Plain Stream. The American Midland Naturalist 148.1:75-89. JSTOR. Web. 26 Apr. 2012. .

(3) Corbet, P.S. 1957. The Life-History of the Emperor Dragonfly Anax imperator Leach (Odonata: Aeshnidae). Journal of Animal Ecology 26.1: 1-69. JSTOR. Web. 26 Apr. 2012. .

(4) Johnson, C. 1968. Seasonal Ecology of the Dragonfly Oplonaeshcna armada Hagen (Odonata: Aeshnidae). American Midland Naturalist 80.2: 449-457. JSTOR. Web. 26 Apr. 2012. .