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Somatochlora semicircularis
Mountain Emerald
Family: Corduliidae
Species account author: Robert Cannings.
Extracted from Introducing the Dragonflies of British Columbia and the Yukon (2002)
Introduction to the Odonata of BC
The Families of Odonata of BC

Photograph

© Bryan Kelly-McArthur     (Photo ID #106766)

Map

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Distribution of Somatochlora semicircularis in British Columbia.
(Click on the map to view a larger version.)
Source: (for the static map) RBCM and BCCDC 2004 ©

Species Information


Description

The sides of the thorax are metallic green with two oval yellow spots, the larger in front. The abdomen sides sometimes have small, dull yellow spots on segments 5 to 8. Male’s appendages shown in figure (the shape gives this species its scientific name, semicircularis). Female’s vulvar lamina shown in figure. Length: ♂ ♀ 50 mm.


Flight Period

B.C., late May to early October; Yukon, mid June to early September.

Genus Description


The scientific name comes from two Greek words: soma, meaning “body”, and khloros, meaning “green”. The English name refers to the yellow or white markings on the sides of the metallic green or bronzy thorax, but most of the distinctly striped species live in eastern North America; western species have spots, short bars or no marks at all. They all have brilliant green eyes. Most North American species are boreal and Appalachian; 13 of 26 occur in our region. Most live around northern or mountain lakes and peatlands.

Species can be hard to identify, especially the females. Look for pale marks on the side of the thorax and white rings between the segments of the abdomen. Hudsonian, Ringed and Lake emeralds have narrow, white abdominal rings. Examine the shapes of the male’s upper appendages and the female’s vulvar lamina. And look for a brown spot at the base of the hindwings – not the membranule, which can also be dark, but an additional spot (Delicate, Muskeg and Whitehouse’s emeralds have it).

Biology

Family Description

Medium-sized dragonflies most often seen around lakes, boggy streams and peatlands in the mountains or in the north. Of 16 species in our region, 13 have Northern or Beringian ranges. The eyes, often brilliant green, meet broadly on top of the head. The shape of the anal loop in the hindwing is distinctive. Adults seldom perch during feeding and males frequently hover when patrolling for mates; when resting, they normally hang vertically or obliquely from vegetation. In flight, a male frequently arches its abdomen, which is often narrower at the base and tip. Larvae are usually squat and rather hairy; they sprawl in the mud and detritus in the bottom of the waters where they live.
Field Notes

The most common striped emerald in B.C., much more common in the south than in the north; rare in the southern Yukon. Thrives in sedge marshes and sedge-lined lakes and ponds, especially where the plants are tall and dense; males patrol and hover over these sedge beds. Also lives in fens and bogs.

Distribution


Montane. Widespread in B.C., and north to valleys in the extreme southern Yukon.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)		COSEWIC
NativeS5YellowNot Listed



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