Wisconsin Odonata Survey

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Enallagma anna  Williamson, 1900
River 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: S3S4    

Distinguishing Characteristics:

The male of this species falls into the category of intermediate-type bluets, which have roughly equal amounts of blue and black on the abdomen. The length of the body varies from 1.2 to 1.4 inches. The female is either pale tan or pale blue with black markings like the male. The legs are less heavily marked with black.

Description of Habitat/Range:

Ranging from central to western United States, this species can be found at slow creeks, streams and rivers, often associated with outflow of warm springs. It has been found at a handful of sites in central and southern Wisconsin.

Flight Season:

Throughout out its range, the flight season is from mid-May to early September. In Wisconsin, the peak of the flight season is late June to late July.


Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
3%
(1)
30%
(11)
59%
(22)
8%
(3)
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 river bluet
Male river bluet. © Dan Jackson

Male river bluet
Photo of Male river bluet
Male river bluet. © Dan Jackson

Male river bluet
Photo of Female river bluet
Female river bluet. © Dan Jackson

Female river bluet
Photo of Female river bluet
Female river bluet. © Dennis Paulson

Female river bluet
Photo of River bluet pair
River bluet pair. © Dan Jackson

River bluet pair



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