Late Dragonflies

Well, it's still dragonfly season!

Yesterday we went to Little Cranberry Lake here in Anacortes. We weren't expecting much, since it had been rainy the last couple days. But the clouds cleared off by mid morning, and at noon it was a nice sunny day, with a temperature of 52 ˚F, so we decided to check out the lake just in case. I'm glad we did.

First, we saw a Tule Bluet, the first damselfly we've seen at the lake since October 9. Here it is:



Next, we saw Autumn Meadowhawks all over the place, with several tandem pairs laying eggs:



They would lay eggs for a bit, in their typical Autumn Meadowhawk way (see my field guide for more details), then they would land on the shore to rest in the sun. Often, this meant that they would land on me, which is always a treat!



Darners were also present—specifically, Shadow Darners. A female was laying eggs on the shoreline for quite some time, and then a male came along and attached to her. He tried to takeoff with her to mate, but she resisted. You can see the male attaching and attempting to takeoff in the pictures below:





Eventually the male gave up, and they separated. The female then landed on the shore to rest:



All in all, quite an active day, especially for so late in the year.

Cool Dragonflies

Well, we're nearing the end of dragonfly season. The days are getting shorter and colder, but there are still a few dragonflies out there. Yesterday, Betsy and I went to Little Cranberry Lake here in Anacortes to check out the action, and we saw quite a bit. Here's the lakeshore:



The temperature was 44 ˚F the entire time we were there, which was approximately from noon to 1:00 pm.

First, we saw quite a few Autumn Meadowhawks; mostly males, but a few females as well. We didn't see any egg laying activity, however.  Here are a few male Autumn Meadowhawks sitting on the bench near the shore:



This is a great place for them to bask in the sun. On the fence nearby a pair was in the wheel position:



Here are a couple males that at first glance appear to be in tandem, but in fact are just resting in close proximity:



Here's another male resting in the bushes just back from the shore:



We also saw darners, both Paddle-tailed Darners (Mr. Happy Face) and Shadow Darners. Here's a male Paddle-tailed Darner perched in the bushes:



For a size comparison, notice the small housefly at the 10 o'clock position.

Here's a close up of this individual, showing the happy face:



It's always wonderful to see this in person.

Finally, here's a female Shadow Darner:



A close-up look shows a bit of a happy face for her as well:



What a lovely November day at the lake.

Wingbeat Phasing in Cardinal Meadowhawks

Here's an expanded version of this earlier post. In this new version, I include screenshots showing the various stages of a wingbeat cycle:

Cardinal Meadowhawks lay eggs while the males and females hover in tandem—this is how the male guards "his" female in this species. Here's a photo of a pair of Cardinal Meadowhawks hovering in tandem over an egg-laying site:



They hover for a second or two as the female gets ready to lay one or more eggs. They then dip down and drop off the eggs. The wingbeat frequency during this process is approximately 48 beats per second—that is, five frames at 240 frames per second.

In addition, it's possible to see how the wing beats of the male and female are related to one another. One might think they flap in sync with one another, but that's not the case. Alternatively, one might think they flap independently, but again, this is not the case. What they do is the following:

(1) The female's hindwings flap first.

(2) After 2/5 of a cycle, that is 144˚ of phase later, the female's forewings flap in unison with the
      male's hindwings. This is the key aspect of the hovering flight.

(3) The male's forewings flap 1/5 of a cycle (72˚) later.

(4) Finally, 2/5 of a cycle (144˚) later the female's hindwings flap for the next cycle.

There's a definite relationship between how the male and female flap, it's just not what one might imagine.

Here's a plot that shows the wing positions for both the male and female as a function of time for two cycles:



This same type of phase relationship between the male and female has been seen in Red-veined Meadowhawks and Autumn Meadowhawks. It will be interesting to see how widespread this behavior is among other species.

For a bit more detail, let's take a look at frame-by-frame screenshots for a typical cycle:

Here's frame 1 of the cycle. In this frame, the female's hindwings are up.

Next, frame 2 (recall that the frames are taken at 240 frames per second).



Frame 3 shows the female's forewings and male's hindwings in the up position.



Frame 4 shows the male's forewings up.



Frame 5 ends the cycle.



Frame 6 starts the next cycle, with the female's hindwings up again.



Very interesting phasing between the male and the female.

Species Spotlight: Emma's Dancer

In the spotlight today is a beautifully-colored damselfly—Emma's Dancer. As with other dancers, this damselfly holds its wing above the abdomen when perched. In addition, it has a lovely lavender color on the thorax. Most of the abdomen is also lavender, with a contrasting blue tip.

Here's a male from Lower Crab Creek near Beverly, WA on the Columbia River:



Before finding this species at Lower Crab Creek, we had seen it only a couple times before near Bend, OR; in those cases, however, we generally saw just a single individual. At Crab Creek, they were the most numerous damselfly.

Here's another male, with a bit different lighting showing off the lavender color:



A final male, with even different lighting. It shows the range of colors observed in this species:



We saw lots of females at Crab Creek as well. Here's a male and female in tandem preparing to lay eggs:



Here's a close up of the female. Notice her light brown color, and light stigmas. In addition, the ovipositor is clearly visible at the tip of the abdomen—all damselflies use ovipositors, but many dragonflies use an egg scoop instead, and just drop their eggs in the water.



The next female has her hindwings spread open, and her abdomen bent, as she fends off the advances of a male:



One final look at the female, showing her wings held well above the abdomen:



This is a species that can be locally numerous, but is not particularly widespread.