Common Nameboreal bluet
SeasonalityAdults fly from late May to mid August in Alberta. Flight season extends in more temperate regions.
IdentificationA large bluet, with adults ranging from 28-36 mm in total length and 17-22 mm in hindwing length. Males are blue (andromorphic), while females are polymorphic and range from light blue to yellow-green (Forbes 1991). Males have narrow humeral stripes and a wide median stripe on the thorax. Black abdominal banding is present in both sexes. In males, the first three black bands occurring on abdominal segments 3 to 5 are typically short and similar in length throughout, however, the black bands may increase in width towards the end of the abdomen in certain northern populations. These males may also possess a large black spot on abdominal segment 2 that touches the rear margin of the segment. Male abdominal segments 6, 7 and 10 are mostly black on the dorsal surface, while segments 8 and 9 are mostly blue. Males have a black subapical bar on the abdominal segment 2 (dorsal). In females, the abdomen is mostly black on the dorsal surface, with pale basal rings on segments 3 to 8. Abdominal segment 8 in females may have more blue or light brown than other segments, and at most may fill segment. When present within abdominal segment 8, the front margin of the black band typically tapers to a point on the dorsal surface. Female abdominal segments 9 and 10 are black. Male eyes are dorsally black and ventrally blue, while female eyes are dorsally dark brown and ventrally light brown. Postocular spots are large and may form dumbbell shape in both sexes. Boreal bluets are virtually indistinguishable from northern bluets (Enallagma annexum) except when viewed under magnification. Male boreal bluets and northern bluets differ in clasper morphology (McPeek 2011). Hagen’s bluets (Enallagma hageni) and marsh bluets (Enallagma ebrium) are similar in colouration, but both are notably smaller, may have smaller postocular spots, and have a larger spot on abdominal segment 2. Familiar bluets (Enallagma civile) are also similar in appearance, however the cerci are longer than paraprocts in familiar bluets, while the opposite is true for boreal bluets (Acorn 2004; Paulsen 2009).