Sexing Common Green Darner dragonflies

Several field marks can be used to identify the gender of female and male Common Green Darner dragonflies (Anax junius).

Female

The following individual, spotted at Huntley Meadows Park, is a female. Female dragonflies have a pair of cerci (superior appendages) that have little or no function. The cerci (sing. cercus) of female Common Green Darners look like almonds, both in color and shape.

20 OCT 2014 | HMP | Common Green Darner (female)

(See a full-size version of the original photo, without annotation.)

Two more field marks verify this specimen is female.

Note the brown stripe extending onto abdominal segment 2. Segment 2 [S2] is typically all pale on males. Also viewing at full resolution, the rear margin of the occiput is not straight. Females have blunt dark colored “teeth” back there which makes the margin look wavy. Source Credit: Ed Lam, author and illustrator of Damselflies of the Northeast, Northeast Odonata Facebook group.

Male

Male dragonflies have three terminal appendages, collectively called “claspers,” that are used to grab and hold female dragonflies during mating: an upper pair of cerci (“superior appendages”); and a lower unpaired epiproct (“inferior appendage”).

The cerci of male Common Green Darners are slightly darker in color and somewhat thicker and more rounded than the cerci of females of the same species. There are points at the tips of the two male cerci, as shown clearly in the full-size version of the following photo; female cerci are pointless, both literally and figuratively.

Male Common Green Darners have a very short epiproct that is used to grip the “teeth” on the back of head of females of the same species.

16 OCT 2016 | JMAWR | Common Green Darner (immature male)

(See a full-size version of the original photo, without annotation.)

The individual in the preceding image is an immature male, as indicated by the purple coloration on his abdomen. As a mature male, his abdomen will be partially covered by blue pruinescence like the one shown below.

06 OCT 2014 | HMP | Common Green Darner (mature male)

Related Resources: Digital Dragonflies, presenting high-resolution digital scans of living dragonflies.

• Genus Anax | Anax junius | Common Green Darner | female | top view
• Genus Anax | Anax junius | Common Green Darner | female | side view
• Genus Anax | Anax junius | Common Green Darner | male | top view
• Genus Anax | Anax junius | Common Green Darner | male | side view

Compare and contrast the cerci of female and male Common Green Darners by viewing the full-size versions of the preceding top views for both sexes and Ed Lam’s excellent composite image, shown below.

Composite image used with permission from Ed Lam.

Copyright © 2016 Walter Sanford. All rights reserved.

Tags: Anax junius, cerci, Common Green Darner dragonfly, Family Aeshnidae, female, Huntley Meadows Park, immature male, Jackson Miles Abbott Wetland Refuge, mature male, Mulligan Pond, pruinescence, terminal appendages, vernal pool, wildlife photography