Wisconsin Odonata Survey

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Enallagma basidens  Calvert, 1902
Double-striped Bluet


Coenagrionidae, Pond Damsel Family
"Most Wanted" Species

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: S2?    

Distinguishing Characteristics:

The male of this species is a blue-type bluet because of its predominantly blue abdomen. One of the smallest bluets, the length of the body varies from 0.8 to 1.1 inches. The male is bluish with a blue face. The thorax is blue but the front is black with thin blue stripes creating a double blue stripes. The female is similar but the pale colors are more extensive and usually tan.

Description of Habitat/Range:

Found in United States, this species prefers ponds with little emergent vegetation, sheltered coves of lakes and along slack stretches of streams. In Wisconsin, it is known from just a few southeastern counties.

Flight Season:

The flight season is from late May to late September in Wisconsin.


Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
24%
(5)
38%
(8)
29%
(6)
10%
(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 double-striped bluet
Male double-striped bluet. © Dennis Paulson

Male double-striped bluet
Photo of Female double-striped bluet
Female double-striped bluet. © Dan Jackson

Female double-striped bluet
Photo of Female double-striped bluet
Female double-striped bluet. © Dennis Paulson

Female double-striped bluet



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