Wisconsin Odonata Survey

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Enallagma annexum  (Hagen, 1861)
Northern Bluet


Coenagrionidae, Pond Damsel Family

The bluets form a group of about 17 similar species in Wisconsin in which the males usually share the characteristics of having blue and black stripes on the thorax, and blue and black markings on the abdomen. In-hand examinations are usually needed to identify them, although they can be grouped into subcategories based on the amount of black showing on the abdomen. Males are easily identified, under magnification, by the shape of their terminal appendages. Females are generally duller than males, and they are more difficult to identify, which is accomplished by subtle differences in the shape of the mesostigmal plates on the top of the thorax. Generally, males are bright blue while the females are green or yellow-green or blue. There are some species that are yellow-orange, a mix of various colors, or black with some blue.

Status-Global/State:

Global: G5     Wisconsin: S4    

Distinguishing Characteristics:

The male of this species is a blue-type bluet because of its predominantly blue abdomen. This species is very similar to, and difficult even for specialists to separate from, the vernal bluet. However, the most recent research suggests specific status for both, and that is how we treat them here. Some odonatists consider these forms to be subspecies. The body length of the northern buet varies from 1.1 to 1.6 inches.

Description of Habitat/Range:

The northern bluet is found usually at ponds, marshes, and some slow streams. Common in Wisconsin, it ranges throughout Canada and northern United States, including the mountains in the west.

Flight Season:

Typical flight season is from late May to mid-July in Wisconsin.


Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
13%
(8)
67%
(42)
17%
(11)
3%
(2)
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 northern bluet
Male northern bluet. © Dan Jackson

Male northern bluet
Photo of Male northern bluet
Male northern bluet. © Mike Reese

Male northern bluet
Photo of Male and female northern bluet
Male and female northern bluet. © Dennis Paulson

Male and female northern bluet



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