Emerald Dragonflies: Corduliidae
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Emeralds (family Corduliidae), or the green-eyed skimmers, fly in most areas of the United States, although species diversity is greatest in the north.
Approximately fifty native Coruliidae species, in six different genera, have been identified:
- Genus Cordulia: American Emerald
- Genus Dorocordulia: Little Emeralds
- Genus Epitheca: Baskettails (ten species)
- Genus Helocordulia: Sundragons
- Genus Neurocordulia: Shadowdragons
- Genus Somatochlora: Striped Emeralds
- Genus Williamsonia: Boghaunters
Generally Corduliidae species are distinguished by the presence of green eyes and dark, bronze or metallic sheen on their bodies. Teneral specimens have brown eyes that change to green withing a few days.
About one half of the Corduliidae species (26) belong to the Genus Somatochlora (Striped Emeralds). As a group, their physical look follows the general pattern of green eyes, clear wings, dark bodies and a pale ring around the second abdominal segment.
While many areas have only a few species present, other areas, such as the Great Lakes, support a dozen species. In areas with multiple species, examining the pattern on the side of the thorax, along with any potential pattern on the abdomen becomes necessary for identification purposes.
Another ten Corduliidae species belong to the Genus Epitheca (Baskettails), and most of these species can be initially identified by the presence of green eyes and a dark abdomen with yellow spots along the side. In areas where baskettail species overlap, wing pattern and cerci pattern serve as identification guides.
The Beaverpond Baskettail (Epitheca canis), pictured at the top of the page, inhabits pond and slow water habitats from coast to coast in northern North America.
Most Corduliidae species inhabit areas east of the Rocky Mountains. The two Boghaunters species, for example, are native to the Northeast and New England.
While two damselfly species are listed as endangered under the terms of the Endangered Species Act, The Hine's emerald dragonfly (Somatochlora hineana) is the only dragonfly on the list. It was listed as endangered in 1995, and small populations can be found in Illinois, Michigan, Missouri and Wisconsin.
The video briefly presents a few native emerald dragonflies in their natural setting.
© 2010-2011. Patricia A. Michaels