Aeshna canadensis

Adult Canada darners, similar to other members of the genus Aeshna, are relatively large, slender dragonflies, and are predominantly dark brown with paler blue or green markings.[4][5] Adults are 64 to 73 mm in total length.[5] The thorax has two vertical stripes on each side, the front with a prominent notch and an extension at the top.[5] The abdomen has spots on most segments.[5] The pale markings are usually blue in males and range from yellow-green to blue in females. The eyes are bluish in males and yellowish or bluish in females.[5] The pale markings may turn gray at colder temperatures.[5]

The green-striped darner is very similar, but is distinguished by minor differences in the shape of the markings and in typically having green thorax stripes.[5] The lake darner is also similar but is larger and has a distinct dark stripe across the face.[5]

The Canada darner was first scientifically described in 1908 by Canadian entomologist Edmund Murton Walker, in the same publication as the first descriptions of black-tipped darner, shadow darner, subarctic darner, and variable darner, .[6]

Canada darners are found from Newfoundland and New Jersey in the east to Yukon in the west.[5] Populations extend further south down the Appalachian mountains to West Virginia and south in mountain ranges to California and Montana.[5][7] There is an isolated population in Nebraska.[5]

nymph

illustration of emergence from larval exuvia

Canada darners spend most of their lives as an aquatic nymph.[7] Larvae are typically found in lakes and ponds, especially bog ponds and beaver ponds.[5] Breeding ponds typically have abundant emergent vegetation.[5] An Ontario study found that the species was restricted to ponds with a pH of no more than 6.2.[8] One study found that larvae may spend either one or two winters underwater before emerging.[7]

Adult males fly slowly along the shores of breeding ponds, sometimes dropping to the surface to search for females.[5] Mating occurs in shrubs nearby.[5] Females lay eggs at water level, usually in marshy vegetation away from shore.[5] Breeding adults are most active in sunny weather.[4]

female laying eggs

Away from breeding sites, adult Canada darners are often found with other darner species in feeding swarms in clearings and along roadways in early evening.[4][5] Adult Canada darners may be seen from June to October.[5]

Canada darners are often considered to be a common to abundant species where they are found.[4][8][9][7] Although the species has not generally been recognised as migratory, a study in Manitoba and Minnesota found that at least some populations of Canada darners undertake north-south migratory movements within their range.[7]

Wikimedia Commons has media related to Aeshna canadensis.

• Canada darner, NJOdes
• Canada darner, eNature.com
• Canada darner, Talk about Wildlife