Paddle-tailed Darner (Aeshna palmata) and Shadow Darner (A. umbrosa) are both rather common and widespread—nearly ubiquitous, I’d say—across the Northwest during the latter part of summer and fall. Not only are they superficially quite similar in appearance, but they are also frequently found flying together. Add to this situation the fact that more and more people are relying on photographs and binoculars instead of nets to identify odonates, and it becomes evident that “new” field marks are needed to sort out these bugs. In this post I’ll summarize the various differences between these two species and explain which in particular seem to be the most useful, at least at this time, for “out-of-hand” identification. Some of these have been well-understood for a long time and some have only recently come to light.
I was able to get out on a couple of warm, sunny days this week. I may not have that opportunity again around here for several months, so I enjoyed it while I could! Several species are still relatively abundant at this time of year in this area, while others are definitely winding down. Many summer species are gone for the year, of course.
Last Sunday (16 Oct) I went to Ice House Lake in Skamania County, Washington. It’s right across SR-14 from the bridge that spans the Columbia River to Cascade Locks, Oregon. There are often several anglers around the margin, but on that afternoon
I had the place, and the odonates, all to myself. It was fun.
The sun made an effort to shine this afternoon (with variable success), and temperatures hovered around the very low 60s. I figured I should take the opportunity to get out and see what I could find flying, so I wandered the grounds and trails of the Columbia Springs Environmental Education Center in Vancouver, Washington.
There wasn’t much variety. Other than a single meadowhawk (Sympetrum) that I spooked from a walkway, all I saw were darners (Aeshna). Two species of Aeshna, Paddle-tailed Darner (A. palmata) and Shadow Darner (A. umbrosa), are particularly common and widespread across the Pacific Northwest during the latter part of the season—mostly from around July on; into November if there are lingering warmish, sunny days. These two species are also very similar in appearance, at least superficially, and are often found flying together.
This was along Mill Creek outside of Walla Walla, Washington a couple weeks ago. There were a lot of meadowhawks (Sympetrum) around—mostly Band-winged Meadowhawk (S. semicinctum) and Striped Meadowhawk (S. pallipes), soaking up a little afternoon sun when the clouds parted. We found this good-sized, plump mantid just off the trail with some Band-winged Meadowhawk remains nearby. I have to assume that the mantid caught and devoured the meadowhawk (its head and thorax, anyway, leaving the wings and abdomen as scraps), and perhaps it was waiting to ambush more that landed within reach of its raptorial forelegs.