Sunday, April 24, 2011

Just a Photo: What I dug up the other day

Here are four dragonfly nymphs (or larvae if you prefer) that I dug up yesterday at Ice House Lake,
Washington. The big spiny one at upper left is a Spiny Baskettail (Epitheca spinigera), the little guy
below that is a young Common Whitetail (Plathemis lydia); going right, the big dark one near the
middle is a Libellula (probably Eight-spotted Skimmer, L. forensis); and the little one at far right is 
either a meadowhawk (Sympetrum) or a whiteface (Leucorrhinia)—I didn’t keep track of which 
nymph was photographed here and I can’t tell which it is from the photo.

Friday, April 22, 2011

A One Species Day, 22 April 2011

With a weather forecast of sunny skies and a high in the lower 60s, I thought I’d get out to a couple of wetlands in the area of Battle Ground, Washington, that I’ve never visited before and see what they were like. I expected to see Pacific Forktail (Ischnura cervula), and I hoped to scrounge up something else—but didn’t. With this being a late spring, I can imagine all sorts of odonate nymphs just itching to pop out. They need more time obviously.

Tuesday, April 19, 2011

ID Challenge #1 Answer

You can see the original challenge with full-size image here. Let’s take a top-down approach to figuring out this thing. To me this means first determining whether it’s a dragonfly (suborder Anisoptera) or a damselfly (suborder Zygoptera), then determining the family, and so on.

Friday, April 15, 2011

ID Challenge #1

I always encourage others to send me their photos (or links to their online photos) of odonates that they have trouble identifying. The tougher ones force me to focus on the little details that often go unnoticed and I really enjoy the challenge. Here’s one for you...

Obviously, this image has been altered. It has been converted to black-and-white and I flattened out the mid-tones to obscure any color patterns that would make the identification more obvious. Also the body and basal portions of the wings have been cloaked by a dense fog for the same reason. I boosted the contrast on what’s left to make the wing venation pop out a little better. I cropped out the ends of the right pair of wings in order to enlarge the left pair (there’s nothing over there that you can’t see in the left pair of wings anyway).

This identification is really about the venation, and this individual can be identified to species pretty easily if you know what to look for. This is a fairly common species in the Pacific Northwest, and it is not restricted to this region. I suspect that many readers will not know what it is, but there’s nothing wrong with that. I hope it will be an interesting and educational experience once the answer is posted.

Post a comment with your answer. Even if you’re unsure of the identity, I’d like to hear from you anyway. In about a week, I’ll post a follow-up with the answer. In the mean time I will switch on moderation of all comments, so they will not appear on the blog until I post the answer.

Have fun and good luck!

Postscript, 19 April 2011

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

Monday, April 11, 2011

Things that are NOT Damselflies

Dragonflies (suborder Anisoptera) are distinctive enough that other insects are never confused for them. Okay, it probably has happened, but it must be pretty rare and I can’t think of any other insects that are even superficially like them. In fact, I’d guess that more often dragonflies are mistaken for other insects such as butterflies. The Halloween Pennant (Celithemis eponina) of eastern North America and the Filigree Skimmer (Pseudolean superbus) of the American Southwest are probably the most butterfly-like odonates on the continent with their boldly patterned wings (black-and-orange on the former, largely black on the latter). I have witnessed Zenithoptera of the Neotropics being mistaken for butterflies (see a post about Zenithoptera lanei here).

Damselflies (suborder Zygoptera) are different. There are other groups of insects with a similarly slender build and long, narrow wings. As you continue reading keep in mind these damselfly characteristics which, collectively, rule out these other insects:

Friday, April 8, 2011

My first flying odonate of the year! (and a bunch of other things)

In my previous post about the Pacific Northwest’s first fliers, I lamented about the cool, wet spring that we’ve been having, and about not seeing any odonates yet. The forecast for today was sunny skies and highs approaching 60° F—still chilly for this time of year, but promising, so I checked out a wetland mitigation/storm water retention site in Vancouver. It isn’t what I consider a great place for odonates, but it’s convenient for a local excursion.