Wednesday, August 28, 2013

ID Challenge #5

At right is an extreme crop of an odonate photographed somewhere in North America—north of Mexico, to be quite ambiguous. I don’t think this one is too difficult to figure out, however what is visible in the image is one of those things which is easily unnoticed if you don’t look for it. Not only can this individual be identified to species, but also its sex and even a little more can be gleaned with some sleuthing.

Leave a comment to let me know what you think it is—the species and sex. If you can tell me anything more based on what you see in the image, include that as well. Comment moderation will be turned on until I post the answer, so they will not be visible in the meantime.

Have fun!

Postscript, 3 September 2013

This challenge is now closed. The answer with a complete discussion is here.

Friday, August 23, 2013

What's that little blue thing? (The Northwest Bluets)

Oh, the little damselfly that has a blue thorax with black stripes and an alternating blue-and-black pattern on the abdomen? That’s a bluet. Which one? Umm...

A generic Pacific Northwest bluet (Enallagma). Note the abdomen
with an alternating blue-and-black pattern, the thorax with blue
and black stripes, and blue postocular spots on top of the head.
Eight species of bluets (Enallagma) are recorded in the region composed of Oregon, Washington, Idaho, and British Columbia and, superficially anyway, they all look alike with their alternating blue and black abdominal pattern and blue and black striped thorax. They really all look alike if you don’t know what to look for, but I’m here to help. I’m not going to explain how to identify each of those eight species in this post—there are field guides and manuals for that, but I’ll give you a few tips to help you narrow down the choices.