Two Common Green Darner dragonflies (Anax junius) were observed flying back-and-forth over a field alongside a vernal pool at a remote location in Huntley Meadows Park (HMP), Fairfax County, Virginia USA — typical feeding behavior for Common Green Darners. Sometimes they would land briefly, perching in shady hidey-holes in the thick vegetation covering the ground. I followed one of the two to a couple of perches.
This individual was very skittish! I was able to shoot one photo at the first perch…
03 OCT 2017 | HMP | Common Green Darner (female)
…and another photo at the last perch. The dragonfly flew toward the tree canopy when I tried to move a step closer.
03 OCT 2017 | HMP | Common Green Darner (female)
It’s relatively easy to identify this type of dragonfly to the species level.
The easiest field mark for identification of a Common Green Darner is that “bull’s eye” on the back of the head. No other [odonate] has it. Source Credit: John Gregoire, Kestrel Haven Wildlife Sanctuary.
On the other hand, it can be more challenging to identify the gender.
Several field marks can be used to identify the gender of this dragonfly. The cerci (sing. cercus) of female Common Green Darners look like almonds, both in color and shape. 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 the second photo at full resolution and zooming in on the head] 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.
Common Green Darner is one of at least five major species of dragonflies known to be migratory in North America. It’s possible the two Common Green Darners that I observed stopped at Huntley Meadows Park in order to “refuel” before continuing their southward migration.
Related Resources
- Sexing Common Green Darner dragonflies, a blog post by Walter Sanford.
- See interactive three-dimensional (3-D) virtual imagery of the five migratory dragonflies, including Common Green Darner, provided by the Migratory Dragonfly Partnership.
- Emergence phenology, uncertainty, and the evolution of migratory behavior in Anax junius (Odonata: Aeshnidae), by Michael L. May, John A. Gregoire, Suzanne M. Gregoire, Maria Aliberti Lubertazzi, John H. Matthews. “…late emerging adults are more likely to migrate.” Source Credit: Abstract.
- Should I Stay or Should I Go, by The Clash
Copyright © 2017 Walter Sanford. All rights reserved.
Tags: Anax junius, cerci, Common Green Darner dragonfly, Family Aeshnidae (Darners), female, Huntley Meadows Park, vernal pool
October 9, 2017 at 7:20 am |
Thanks Walter, nice article. The easiest field mark for ID of a Green Darner is that “bull’s eye” on the back of the head. No other has it. J.
October 9, 2017 at 11:52 am |
Thanks for reminding me, John. Although I was only trying to explain how to determine the gender of the dragonfly, I think I may revise the post to explain how the bull’s eye field marker can be used to identify the species. Can I quote you?