Jul 16 2011

Threat Display

Published by at 7:30 am under Insects, Fish, Frogs


This dragonfly doesn’t perch like this for fun.  His pose is a threat display.

This is a male Common Whitetail (Plathemis lydia), a showy dragonfly with a white pruinose abdomen and clear black-striped wings. 

Common Whitetail males are highly territorial.  They live near ponds, marshes and slow moving rivers where they defend 10 to 30 yards of the water’s edge and conspicuously chase away all other males.  When they’re not chasing they pose like this to let the others know they mean business. 

Their white pruinose backs are the warning sign.  Pruinose refers to the dusty, frosted appearance caused by a pigment that covers the insect’s ”skin.”  In nature, pale-colored pruinescence often reflects ultraviolet light.  If so, this bug probably glows in sunlight.  I wish I could see it!

Female Common Whitetails look quite different because their tails aren’t white, a feature that probably protects them from male aggression. 

Watch near water and you’ll see the males patrolling.  Try to find the females too, even though they’re not so flashy.  

I’m happy when I see them.  These dragonflies eat flying insects, including mosquitoes!

(photo by Chuck Tague)

6 responses so far

6 Responses to “Threat Display”

  1. sharon Leadbitteron 16 Jul 2011 at 8:20 am

    They have a bunch of these at Beechwood Farms in Fox Chapel … gorgeous … and very nonchalant with humans

  2. Marjorie Van Tasselon 16 Jul 2011 at 4:48 pm

    See quite a few of these at Crooked Creek on both ponds. Also a few Pond Hawks and Spangled Dashers, and other neat Odonata…interesting article, Kate–thanks, I did not realize the reasoning for this “pose/perch”. I have seen the females and it their bodies resemble a dagger or lance or other weapon, in a way, in my opinion.

  3. Mary DeVon 17 Jul 2011 at 10:21 pm

    I used to see one a lot last summer, patrolling by Schenley Park swimming pool. Maybe he thought it was a pond?

  4. vern maukon 27 Jul 2012 at 8:45 pm

    near our very small pond. long slilm white body dark, (black) wings , the wings look like dadrk paddles as part of them are transparent…..????

  5. Angelina Dawn Wetterlingon 02 Aug 2012 at 11:02 am

    Today I took half an hour to catch a few pictures of the male. It was beautiful while it roamed threw our vegetable gardens :) there is a huge saloo about half a mile west of us and a few small ponds about a mile north of us.

  6. Amieon 12 Aug 2012 at 5:15 pm

    Hey!

    I have a few of these outside my apartment. We have water features here so the water territory makes sense. They are so beautiful, that I finally looked them up, very cool!!

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