Which Dragonfly? - Libellula pulchella

Our 2 cents

We vote for Libelula pulchella. MOST female L. pulchella have a relatively narrow dark area at the wingtip, exposing most of the stigma. MOST female Plathemis lydia have a wider dark area at the wingtip, covering most of the stigma. The trailing edge of the hind wing appears straighter in L. pulchella. I don't remember ever seeing a L. lydia perched more than 3 ft. above the ground. This specimen appears to be on a higher perch.
For scans of a live female P. lydia check here.
For scans of a live female L. pulchella check here.
For highest resolution, after opening the image, click on "get original uploaded photo" beneath the image.

… Gayle and Jeanell Strickland, 22 November, 2006 - 9:46pm

Libellula sp.

This is a female Libellula, either L. lydia (Common Whitetail) or L. pulchella (Twelve-spotted Skimmer). The only way (to my knowledge anyway) to tell the two apart is by the abdominal pattern.

… Cliff Bernzweig, 22 November, 2006 - 4:23pm

Cliff, what do you think of the two yellow lines

on the side of the thorax. They have always struck us as being more steeply angled in Plathemis while in Libellula the second is almost horizontal. That may just be a figment of our imagination, so that's why we're asking. Based on that we would call this L. pulchella, not that it actually matters, even though we can't see the abdomen. What has your experience been?

… john and jane balaban, 22 November, 2006 - 5:13pm

Interesting

To be honest, I never noticed or paid attention much to the thoracic stripes of these two species. It is easy to overlook the common species when one focuses on finding the rare and elusive species as I have done. However, I searched through my photos and I did notice a slight difference. Here is a composite photo of the thorax of each dragonfly. The rear (metepimeral) stripe has a definite bend in lydia, somewhat like a boomerang, whereas in pulchella it is pretty much straight. I'm not sure you can really see the metepimeral stripe on this bug quite well enough to rule out either. I would lean towards pulchella based on the relatively skinny abdomen (I think lydia is typically a chunkier species), but I am not totally confident of that ID.

… Cliff Bernzweig, 22 November, 2006 - 7:51pm

Thanks --

liked the composite image. We'll have to keep our eyes open and see if we can identify them by their thorax. The abdomen is so distinctive you normally wouldn't look further.
Thomas, this looks like your best answer. We probably won't move this one to the guide, but will Frass it after a couple of weeks. It will stay there for thirty days before it's deleted.

… john and jane balaban, 22 November, 2006 - 8:08pm

I took a look at

my images. The anterior thoracic stripe in lydia, both males and females, consists of a long dorsal dash and a separated ventral dot. Can be seen in Cliff's composite image and here:

In pulchella, the anterior stripe is just 1 long dash.

… A.W. Thomas, 22 November, 2006 - 9:28pm

Good eye

Didn't notice that either. It looks as if the anterior stripe extends across the suture dividing the pterothorax and the prothorax, forming a pale dot on the prothorax, whereas in pulchella the stripe stops at that suture.

… Cliff Bernzweig, 22 November, 2006 - 10:14pm

Nice --

We copied both of these comments to the L. pulchella info page so they wouldn't be lost if we Frass this image. Please feel free to edit or amend them since we moved them without your permissions.

… john and jane balaban, 22 November, 2006 - 9:39pm

Wow...

...all this from a bad image! Hehe.

… Thomas Wilson of Armistead Gardens in Baltimore City, 22 November, 2006 - 10:44pm