InstructionsUse the keyGroupsfamAnatomy
Phylum Arthropoda
Class Insecta
Order Odonata
Suborder Anisoptera
Family Corduliidae
Common Name Emerald Dragonfly
Distinguishing Characteristics
  • Short and broad bodies (1, 2)
  • Spoon-shaped prementum (1)
  • deeply scalloped palpal lobes (1)
  • Distal margin of each palpal lobe is either smooth or has smaller, more regular dentations (2)
  • Head lacks a prominent frontal horn between antennae base (2)
  • Ventral surface of prementum has a medial groove extending from the basal hinge to halfway along the ligula (2)
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     Mostly lentic environments such as marshes, cool ponds, swamps, and littoral regions of lakes (1). Some species are found in the benthic environment of streams among debris (1).
     The genus Tetragoneuria is the most common genus found in northeastern regions of the US. Occurring frequently in temperate and southern taiga regions; regions that border coniferous forests. The genus Tetragoneuria can be found as far south as Florida and Texas (3).

Life History
     Life cycles on average last two-to-four years in the northern hemisphere, and shorter life cycles in the southern hemisphere (1). Larval distribution has been recorded to be discontinuous and grouped, often occurring within short distance of the shoreline in shallow water. The method of egg dispersal may be an influencing factor to these findings (3). Larvae in their resting state have been observed burrowing into detritus deposits of small streams. In the lower peninsula of Michigan, the species T. cynosure larval stages persist for two to three years depending on water column temperature (3). Larvae emergence of some species may be synchronized and lead to the formation of large swarms (1).
     The adult flight period is predominately from May to early July (1). Oviposition sites often overlap with mating sites, which suggest that several generations of Corduliidae are born and die in the same geographic location (4). Adult life span varies geographically. In northern Michigan, the adult life span of the species Tetragoneuria cynosure ranges from 3.5 weeks to 8.0 weeks, suggesting that climate has an influence on adult life span duration (3).
     Adults are most active during midday (5). The mating and feeding schedule has been correlated to the amount of sunlight in both Michigan and in Spain (3, 5).

Feeding Behavior
     Corduliidae are carnivorous predators. Larvae first consume small protozoans and similar-sized metazoans. Then gradually as the mouthparts continue to morph, larvae begin preying on larger, more variable prey such as microcrustacea (3).
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(1) Thorp, J.H. and A.P. Covich. 2010. Ecology and Classification of North American Freshwater Invertebrates, pp. 587-657. Elsevier Inc. Boston.

(2) Cummings, K.W. and R.W. Merritt. 1996. An Introduction to the Aquatic Insects of North America. Kendall and Hunt Publishing Company. Boston.

(3) Kormondy, E.J. 1959. The systematics of Tetragoneuria, based on ecological, life history, and morphological evidence (Odonata: Corduliidae). Miscellaneous Publications, Museum of Zoology. 107.

(4) Ubukata, H. 1984. Oviposition site selection and avoidance of additional mating by females of the dragonfly, Cordulia aenea Amurensis selys (Corduliidae). Restoration and Population Ecology 26: 285301.

(5) Rivera, A.C., C. Utzeri and S.S. Carbone. 1999. Emergence and adult behavior of Macromia splendens (Pictet) in Galicia, northwestern Spain (Anisoptera: Corduliidae). Odonatologica 28: 333342.