Argia moesta

Powdered Dancer


Argia moesta, Powdered Dancer male

Family: Coenagrionidae

Length: 37 - 42 mm

 

The Powdered Dancer is an interesting species. The male has a mostly white head and thorax, an unusual trait for a damselfly. Moreover, this is one of the few damselfly species where the female is more colorful than the male. In addition, the female comes in two distinct color variations.

Powdered Dancer, Argia moesta, pair in tandem

 

Watching Odes at ponds, you would seldom or never encounter a Powdered Dancer. Begin watching at rivers, however, and this species may be one of the first you will encounter. The species also appears occasionally at large lakes with rocky shores.

The male is a dark-colored damselfly that develops extensive pruinosity as it matures. (Pruinosity is a waxy, light-colored substance that builds up on an odonate's body, obscuring whatever coloration lies beneath.) In the photos above and at left, the male's black and brown coloration is partly obscured by the white pruinosity.

Powdered Dancer, Argia moesta

 

As for females, some are light blue on the head and thorax, and might almost be mistaken for a male or female Blue-Fronted Dancer. Male Blue-Fronted Dancers would have a blue tip to the abdomen, however. A female Blue-Fronted Dancer would be mostly black on top of the abdomen, and the sides of abdominal segment nine would be darker.

Females also appear in a brown variation, which may have greenish overtones to it as in the photo at above left.

One of the great twentieth century entomologists, Donald J. Borror, studied this species by marking individuals and following individuals’ life history. Among other things, Borror concluded that "The adults do not fly very far, and their movement from place to place is rather slow. Most of the movement is to and from the river; there is relatively little movement upstream or downstream" (Borror 1934.)

Borror reported that at the river the sex ratio was about even, but if one takes into account the individuals living in field and meadow as well, the sex ratio is actually about 2:1 favoring the females.

 

Powdered Dancer male, Argia moesta

 

Powdered Dancer, Argia moesta 

Like the thorax, the face is soon covered with pruinosity.

 

Powdered Dancer, Argia moesta

There is no particular pattern on the male's abdominal tip; just pruinosity that increases with age.

 

Powdered Dancer, Argia moesta female

Pictured above is the blue color variety of the female Powdered Dancer. Note that unlike the female Blue-fronted Dancer, the female Powdered Dancer has lighter coloration on top of the abdomen, not black.