RE: RE : [Odonata-l] Texas Dragonfly to identify...

[George L. Harp]

Hello to all,
 
Erythemis simplicicollis was the first species that I recorded for every county of Arkansas, while Pachydiplax was not far behind.  In sheer numbers, E. simplicicollis has no equal.  I, too, have noted on occasion that this species will form 95+ percent of the odonates.  The sites are often not blessed with a variety of habitats and the water quality is somewhat impared, primarily with organic silts, causing low DO values.  The first place I noticed this was at some sites around Reelfoot Lake in extreme NW Tennessee.  I have also seen it at times around Mallard Lake in the Big Lake Wildlife Mgmt. Area of Mississippi County, AR.  The E. simplicicollis can overwhelm other species.  Again, a few Pachydiplax are usually around, and an occasional Anax junius or Tramea lacerata.  I have also noticed, Dennis,that damsels are extremely scarce, which I have speculated was probably due to predation by the concentrations of E. simplicicollis.  Several years ago while I idly watched an Erythemis fly across in front of me, something suddenly zoomed up from the ground, hit the Erythemis so hard that it carried it up several inches farther before quickly taking it to the ground.  I moved over as quietly as possible to see who this vicious hunter was.  To my surprise, it was another Erythemis. 
 
Best,
 
George    

________________________________

From: odonata-l-bounces at listhost.ups.edu on behalf of dennispaulson at comcast.net
Sent: Tue 7/14/2009 9:09 PM
To: Glenn Corbiere
Cc: Odonata List Server
Subject: Re: RE : [Odonata-l] Texas Dragonfly to identify...


Glenn, 

You spoke volumes when you tallied up those dragonflies. I've had the same experience, once at Fort Bend State Park in the same part of Texas and often in Florida. I couldn't believe that such a nice series of wetlands as those at Fort Bend supported virtually nothing but those two common species. Often Slaty Skimmer, Libellula incesta, is #3 behind the first two in these situations, but far less common.

It may be noteworthy that that rapacious predator Erythemis simplicicollis is one of the most common dragonflies now in the Southeast. It's conceivable that its abundance is the cause of the disappearance of damselflies from many parts of the Southeast in midsummer. I'm still working on that hypothesis. However, Erythemis eats a lot of Pachydiplax too, and that species is still superabundant. The other alternative is that these two species are favored by anthropogenic changes in wetlands, but a lot of the wetlands where they are common seem on superficial examination to be nice habitats. However, perhaps they have undergone more eutrophication than one might think. Why would the larvae of these two libellulids become so common?

Dennis

----- Original Message -----
From: "Glenn Corbiere" <gcorbiere at dragonhunter.net>
To: "Michel Pilon" <Michel.Pilon at rncan-nrcan.gc.ca>, "Odonata List Server" <odonata-l at listhost.ups.edu>
Sent: Tuesday, July 14, 2009 6:46:43 AM GMT -08:00 US/Canada Pacific
Subject: Re: RE : [Odonata-l] Texas Dragonfly to identify...


Michel,

I was visiting Texas a few years back on a business trip, I was near the coast Southeast of Houston. I spent an entire day on three beautiful wetland areas. I saw 6,010 (in round numbers) different individual dragonflies and or damselflies.

5,000 were Erythemis simplicicollis / Eastern Pondhawk
1,000 were Pachydiplax longipennis / Blue Dasher
The remaining 10 were a total of about 6 or 8 other species.

I was not amused.

Be that as it may, you have one very common dragonfly there, and probably the most common dragonfly around any of these parts, but you have one of the nicest photos I've ever seen of that species!

So ultra common or not, Congratulations on a great photo!

Glenn



Glenn Corbiere 
100 Prospect St. 
Chester, MA. 01011-9657 

www.dragonhunter.net