E-Fauna BC Home

Somatochlora septentrionalis
Muskeg Emerald
Family: Corduliidae
Species account author: Robert Cannings.
Extracted from Introducing the Dragonflies of British Columbia and the Yukon (2002)

Photograph

© Dennis Paulson     (Photo ID #1224)

Map

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

Species Information


Description

Similar to Whitehouse’s Emerald, but less common. Both have a dark spot at the base of each hindwing. Both have brassy green thorax sides with a short, indistinct yellow-brown stripe below the base of the forewing (sometimes an indistinct yellowish patch below the base of the hindwing). The difference is in the shapes of the male’s appendages and female’s vulvar lamina. Length: ♂ 43 mm, ♀ 44 mm.


Flight Period

B.C. and Yukon, mid June to late August.

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

Rare. Lives in bogs and fens where males patrol shallow ponds and pools. Typically, these pools are set in sphagnum and other mosses and are characterized by soft, mucky margins and scattered sedges. Males fly irregularly over the open water and around the pool edges, hovering infrequently.

Distribution


Northern. From about 54°N on the plateaus of central B.C. and about 52°N in the Coast Mountains to the southern Yukon.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
COSEWIC
NativeS4YellowNot Listed



BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.