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Clamp-tipped Emerald



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Somatochlora tenebrosa

Say, 1839


Order Odonata
Suborder Anisoptera
Superfamily Libelluloidea
Family Corduliidae
Genus Somatochlora
Species tenebrosa (Say, 1839) [Libellula]


Identification

This common eastern species has been seen rarely as far west as Arkansas and Oklahoma. It is distinct, among the species in the region, in having a single large circular pale spot laterally on abdominal segment 2. It has an orange-yellow face and the top of the head is deep metallic blue or black. The thorax is brown and metallic green with well-developed pale stripes laterally. The wings are clear, but occasionally becoming tinted with amber. The legs are black. The abdomen is brown with metallic reflections. Segment 2 is as above. Segment 3 has a short dorsolateral spot and a larger ventral spot. The large angulate cerci of the male are distinctive. The female has a long, compressed ventrally projecting ovipositor.

Size

Total length: 48-65 mm; abdomen: 33-46 mm; hindwing: 33-42 mm.

Similar Species

No other Emerald in our region has a single large circular spot laterally on the second abdominal segment and the male's cerci are unique.

Habitat

Small forested streams with intermittent riffles and pools.

Discussion

This species is typical of the genus, flying in the early morning or late afternoon and evening. It is known to have a preference for shade. Wilson (1912 ) observed this species "...patrolling back and forth just after sunset in one corner of an old pasture near a small brook at the foot of the mountains. They were strong and rapid fliers..." Males will often hover over the creeks and streams they patrol.

Distribution

Widespread throughout eastern U.S. and Canada.