Wisconsin Odonata Survey

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Aeshna subarctica  Walker, 1908
Subarctic Darner


Aeshnidae, Darner Family
"Most Wanted" Species

The mosaic darners of the genus Aeshna (aka blue darners) are large, strong-flying dragonflies with late-season flight periods. Most are similar to each other in size and general coloration, so in-hand examination is usually necessary to identify them. The most important distinguishing characteristics for this genus are the shapes and colors of the pale stripes on the sides of the thorax, especially the first or anterior stripes (here referred to as anterior thoracic side stripes [ATSS]), and the shapes of the cerci (upper pair of claspers) at the tip of the abdomen (whether paddle type or wedge type). Other marks that are often helpful include the presence/absence of a black line across the face, and the sizes of the pale spots on top of the abdominal segments (S), including the presence/absence of a spot on S10. Refer to the images of Aeshna species on the species pages of this website to compare shapes of thoracic side stripes and consult any dragonfly field guide for illustrations of the claspers (some guides are listed in the Resources Section).

Status-Global/State:

Global: G5     Wisconsin: S1S2?    

Distinguishing Characteristics:

Both genders are readily distinguished from other mosaic darners by the shape of the anterior thoracic side stripes (ATSS), which are bent slightly forward in the upper half. Thin, pale lines are usually visible between and in front of the side ATSS. There is a moderately thick black line across the face. The eyes appear more greenish, less bluish, than most other mosaic darners. Males have paddle-type claspers. Females may be blue form, green form, or yellow form.

Description of Habitat/Range:

Ranging throughout Canada and northernmost United States, this species can be found at bog ponds, deep fens with well-defined edges, and northern swamps with abundant Sphagnum and other mosses. It occurs in Wisconsin at a handful of sites in a cluster of northern counties.

Flight Season:

Throughout its range, the flight season is from early June to early October. In Douglas County, Wisconsin, most adults are seen in late August and early September.


Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
13%
(2)
40%
(6)
47%
(7)
Shading illustrates monthly percentages of the total flight season records for the species. Each flight season record is a unique date/location/observer combination where one or more adult or an exuvia was recorded (excludes nymphs). The actual number of flight season records for each month is shown in parentheses.

Flight seasons begin earlier in the southern part of the state, often by a week or more. Also, flight charts may not be accurate for rare species because of few data available.
View user-submitted photos

(Click on photos to enlarge)
Photo of Male subarctic darner
Male subarctic darner. © Dan Jackson

Male subarctic darner
Photo of Male subarctic darner
Male subarctic darner. © Ryan Brady

Male subarctic darner
Photo of Teneral female subarctic darner
Teneral female subarctic darner. © Dan Jackson

Teneral female subarctic darner
Photo of Teneral female subarctic darner
Teneral female subarctic darner. © Dan Jackson

Teneral female subarctic darner



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