Monday, May 9, 2011

Identification: Dragonflies versus Damselflies

I’ll be posting periodically on odonate identification and right at the top—dragonflies versus damselflies, is a natural place to begin. As usual, I’ll be using the term “dragonfly” (and the plural “dragonflies”) in the strict sense meaning only odonates in the suborder Anisoptera, excluding damselflies which are in the suborder Zygoptera. For a refresher on these terms, see my post Is that a Dragonfly or an Odonate?

Generally speaking dragonflies and damselflies really aren’t all that similar, but it’s useful to have a good fundamental understanding of the features that differentiate them. At the very least you can impress your friends, right? So below are the features that will tell you whether you’re looking at a dragonfly or a damselfly in roughly the order of the bigger, more obvious to the itty parts that require closer scrutiny. I mostly cover adults since that’s what most people see, but I’ll talk about nymphs a bit at the end.

Wednesday, May 4, 2011

A Dragonfly Emergence Sequence

While on the southern coast of Oregon last weekend I checked a pond in Bandon for odonates to see what was flying. There were lots of Pacific Forktails (Ischnura cervula) and a few Tule Bluets (Enallagma carunculatum) flying, but no dragonflies. However, I did come across two American Emeralds (Cordulia shurtleffii) that were in the process of emerging. Below is a sequence of shots of one of them which I took periodically while I also looked for nymphs in the water. I included the time stamp in the upper right corner (hh:mm:ss), so you can see how much time elapsed between each shot.