Pond Damselflies
Family Coenagrionidae
Genus Enallagma
Slender Bluet (Enallagma traviatum westfalli)



"Black-type" Bluet – the males abdomens are predominantly black when viewed from above. This damselfly has large eyespots connected by an occipital bar. Similar species – Stream Bluet (Enallagma exsulans).


Flight season: late June to early September.

Population: common, but mostly confined to the marshy shoreline of Stoco Lake, particularly near treed areas. A couple of individuals have also been encountered east of Tweed along the trans-Canada Trail. This population of Slender Bluets is far north of its known range (southwestern Ontario).

Length: about 30 mm, aptly named, a very gracile damselfly. The large blue eyespots, extensive blue on the thorax, and very thin black shoulder stripes separate this damselfly from other local Enallagma species.


Tweed, Ontario, the north shore Stoco Lake near the pavilion: marshy shoreline, relatively shallow water with mud bottom supporting sedges and rushes, pondweeds, Fragrant Water Lily, Blue Flag, Sagittaria spp and Pickerelweed.
Male Slender Bluet (Enallagma traviatum westfalli) – the male's prominent cerci are noticeable in the field (July 29, 2013).

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Views of the claspers of another male Slender Bluet (Enallagma traviatum westfalli). Several males were captured and studied, the profiles of their cerci suggest this is subspecies westfalli (July 25, 2013).
Slender Bluet (Enallagma traviatum westfalli) – the red outline superimposed on the photo is based on Ed Lam's illustration of the terminalia of subspecies westfalli, Page 61, Damselflies of the Northeast, 2004.

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Female Slender Bluet (Enallagma traviatum westfalli)
July 27, 2013

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Slender Bluet (Enallagma traviatum westfalli) – a tandem pair resting on the sand (July 26, 2013).

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Slender Bluet (Enallagma traviatum westfalli) – a rather tame mating pair taking advantage of a handy place to perch (July 26, 2013).

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Slender Bluet (Enallagma traviatum westfalli), wheel – several mating and tandem pairs were observed in this area (July 28, 2013).


Tweed, Ontario, the north shore Stoco Lake, east of the boat pier: marshy shoreline, relatively shallow water with mud bottom supporting sedges and rushes, pondweeds, Fragrant Water Lily, Blue Flag, Sagittaria spp and Pickerelweed.
A set of images illustrating the attributes of a male Slender Bluet (Enallagma traviatum westfalli) – note the profile of the cerci (September 10, 2014).


Slender Bluet (Enallagma traviatum westfalli) – the red outline superimposed on the photo is based on Ed Lam's illustration of the terminalia of subspecies westfalli, Page 61, Damselflies of the Northeast, 2004.

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A collection of images illustrating the features of a female Slender Bluet (Enallagma traviatum westfalli) – note the uniquely shaped black mark on S8 (August 19, 2014).