Is There an Entomologist in the House?

Lately, this blog seems like online field notes, but the truth is I am spending a lot of time reading and thinking about bugs, especially dragonflies. The lake behind campus is replete with four-spotted pennants, or Brachymesia gravida, a type of skimmer. Identifying this species has been quite a challenge.

I took my first pictures of four-spotted pennants a couple of weeks ago. At the time, I didn't know their name. I found three color variations, and at first I mistakenly believed that I had found two new dragonfly species [new to me, at least]. One version I called [in entirely unscientific lingo] chocolate-blueberry:


The eyes do look like pools of Hershey's milk chocolate while the wings seem to have four chocolate fingerprints on them, as though God were snacking on Kisses while assembling these little guys, holding them up to study his handiwork. From a distance, the thorax and abdomen appear black, but once I got close enough, I noticed a blue tone, as if they were a fruit and chocolate blend.

None of the three dragonfly guide books I have recently purchased identify this particular species, so I was at a loss for a common/scientific name until I happened across a similar photo at Odonata Central. I now know that the above individuals are male four-spotted pennants, their coloring the giveaway. Once I had a name, I went to Bugguide.net to confirm the identity, and it was at this website where I realized that the second new dragonfly I had found at Lake Pamela was an immature male of the same species.

The second color variation looks like this:


The colors might be strikingly different, but I wasn't surprised to discover that they were the same species because the "chassis" of the two versions are identical. When I compare "chocolate-blueberry" above to these specimens, I notice the similar position and shape of the "headlights," the styling of the "passenger compartments," the identical amounts of "trunk" space. The immature male has the flashy colors of youth while the mature male has a "paint job" that indicates his elder statesman status.

Dragonflies, I've learned, go through dramatic color changes as they mature. I believe that for a four-spotted pennant, the "tweenie" version looks like this:


At first, I thought this duller-colored one might be a female, but after I looked more carefully, I noticed the "chocolate fingerprints" beginning to appear on the wings, the bright colors fading into shades that could darken to the blue-black of the mature male. That's my reasoned guess, anyway.

So where are the women? I haven't observed a single mating pair during my "field work." Female dragonflies don't hang out near the water; they only make an appearance to breed. Shorelines are male territory. I did spy this dragonfly in the woods beside the lake:


Her[?] coloring might indicate a female. Female scarlet and roseate skimmers, for example, are yellowish. I have observed no scarlet and roseate skimmers at the lake, though. I was hoping she[?] was a female four-spotted pennant, but Digital Dragonflies shows the chocolate fingerprints on the female as well as reddish eyes.

I wish I knew an entomologist, especially someone who knew odonata, as I get frustrated and confused!