All 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”).
A Cobra Clubtail dragonfly (Gomphus vastus) was spotted at Riverbend Park, Fairfax County, Virginia USA. Two field markers indicate this individual is a male, as shown in the following annotated image: 1) it has three terminal appendages; and 2) its hind wings are slightly “indented.”
(See a full-size version of the original photo, without annotation.)
All male dragonflies have three terminal appendages, right? Look closely at the preceding annotated image. Notice there are four “prongs” at the posterior end of the abdomen. Cobra Clubtails feature a two-pronged epiproct. Just thought I should clarify any cognitive dissonance that may have been caused by looking at these images!
Males perch on shore, or on rocks in rocky rivers, with abdomen elevated, then fly beats up and down. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 5952-5953). Princeton University Press. Kindle Edition.
Some species of dragonflies regulate their body temperature by perching in the “obelisk position”: the tip of the dragonfly’s abdomen is pointed toward the Sun, minimizing the surface area of the body exposed to direct heating by the Sun’s rays, thereby avoiding overheating. Given the orientation of Cobra Clubtail relative to the Sun, I’m guessing this type of perching behavior is probably intended to mark territory and attract mates.
Editor’s Note: Female Cobra Clubtail dragonfly terminal appendages will be featured in a follow-up post: Cobra Clubtail dragonflies (females).
Copyright © 2016 Walter Sanford. All rights reserved.