Tuesday, February 21, 2017

Species Spotlight: Blue Dasher

Well, we've finished up with the dragonflies with "black" in their name, and are now onto the "blue" dragonflies. First up, the Blue Dasher.

This is one of my favorite dragonflies for a number of reasons. First, it's very widespread in its distribution, so you're likely to see one almost anywhere you go dragonflying. Here's it's range map:

The only blank areas are the upper plains and Rockies.

Second, it's very cute and photogenic. The Blue Dasher strikes delightful poses for the photographer, and lands repeatedly on favorite perches. Here are a couple shots of the male Blue Dasher:

The blue color of the Blue Dasher is produced not by pigments, but by light scattering from the microscopic structures on its body—in much the same way that the scattering of light gives the sky its blue color.

The large area on the top of the Blue Dasher's eyes, where you can just make out the lattice of individual eyes (the ommatidia), is known as the dorsal fovea. It is the part of the eye that gives the dragonfly its highest resolution vision. If you look straight down on the dorsal fovea you see large black pseudopupils, as shown below. (By the way, the white spots are reflections of the sun.)

Female Blue Dashers are completely different in appearance. They are cryptically colored with a brown background and numerous yellow stripes:

The Blue Dasher—beautiful, widespread, easy to photograph. This species has it all.

Friday, February 3, 2017

The Whisperer To Speak at Sound Waters!

I'll be giving two talks tomorrow at the Sound Waters environmental conference on Whidbey Island. The conference is advertised as "a one day university for all—on all things Puget Sound." Should be a lot of fun. The firs talk will be a general introduction to dragonflies in Puget Sound, and the second talk will focus on darners and their interesting behavior.

Here's the handout for the talks:

See you there tomorrow!

Sunday, January 29, 2017

Species Spotlight: Black Setwing

We conclude our tour of species with "black" in their name with the Black Setwing.

I've only seen this dragonfly twice so far, once at Tortilla Creek and once at the Gilbert Water Ranch, both in Arizona. It's a distinctive little dark bluish dragonfly that looks a bit like the Plateau Dragonlet, but is thinner and rather spindly.

Here's a look at one at the Gilbert Water Ranch:

I hope I get to see more of them this year.

Saturday, January 28, 2017

Species Spotlight: Black Saddlebags

Next up in our Spotlight series is the Black Saddlebags. This species is named for the large black patches ("saddlebags") in its hindwings. You can see the saddlebags in the following photos:

Notice how the saddlebags are confined to the hindwings—the forewings are clear.

What is the purpose of the saddlebags? Well, one purpose in hot climates is to cast a nice shadow for the abdomen to bask in as a way of cooling the body. This is what's going on in the next photo, which was taken in Arizona on a 102˚ F day.

Take a look at the long, thin appendages in the above photo. Perhaps these appendages help with the unique egg-laying process in saddlebag species, in which the male and female detach and then reattach many times in succession.

To be specific, saddlebags lay eggs in a way that is similar to the Apollo lunar landing missions—on those missions the command module remained in orbit while the lunar lander descended to the surface, the astronauts did their exploring, and then the lander returned to orbit to reattach to the command module. In saddlebag species, the male and female hover in tandem over an egg-laying site. When the male is satisfied the coast is clear, and no fish are lurking nearby, he quickly droops his hindwings to signal the female that he is releasing her. She then descends to the water's surface and lays an egg. As she rises from the water the male descends and intercepts her. He then reattaches, and the pair flies off in search of another egg-laying location.

Look for this behavior the next time you see Black Saddlebags while dragonflying. You have to watch carefully, though—the entire process takes only about a second.

Thursday, January 26, 2017

Species Spotlight: Black Meadowhawk

A Black Meadowhawk sounds a bit like an oxymoron. After all, the other meadowhawks in our area are red. In fact, being red is almost a defining characteristic of the meadowhawks—with the exception of the Black Meadowhawk.

The Black Meadowhawk is quite small and dainty, and is easy to miss. It often perches on the damp, dark ground near the shore, where it blends in splendidly. It can also be a bit fidgety and hard to approach.

Here's a male showing off from a prominent perch above the ground.

Notice that the body of the Black Meadowhawk isn't a deep, dark black, as in an American Emerald or a Dot-tailed Whiteface. The body of this species is a dull black, with a number of dark yellow spots as well.

Here's a side view, showing the hamules quite clearly.

The next photo shows the yellow spots and clear wings.

Females are more yellowish in overall color, and even more difficult to spot when perched.

Wednesday, January 25, 2017

Species Spotlight: Beaverpond Baskettail

Beaverpond Baskettail. What an interesting, alliterative name for a dragonfly. The beaverpond part of it makes sense, given it's habitat, but the last part of the name is a bit odd—especially with those two ts together.

In any case, this is a dragonfly that isn't seen that often in my home area, so it's always a treat when I get to see one. A member of the emerald family, it has beautiful eyes—as you can see in the older male (notice the scuffed wings) shown below:

This male shows the basic features of the species, including the small dark patch in the wings, near the base, and the "pistol-shaped" appendages that distinguish this species from the similar Spiny Baskettail, whose appendages have a simple shape. Some people say the upper appendages (cerci) look like the head of a dog. To me they look like a pistol pointing forward, with the handle coming down at a right angle to the barrel. Also, notice that its front two legs are "tucked up" behind its head—a common resting position.

As mentioned, the eyes of Beaverpond Basketballs are their most striking feature. Here is young male showing off his lavender eyes:

What beautiful eyes you have. Here's a closer look:

If you get a chance to see this species, be sure to get a good look at its eyes!

Tuesday, January 24, 2017

Species Spotlight: Band-winged Meadowhawk

Our next species is another meadowhawk—the Band-winged Meadowhawk. This is a species that is distinguished by extensive amber wing patches.

Here's a male Band-winged Meadowhawk, giving a good view of the wing patches:

Notice that the patches are darker on the hindwings than the forewings, but even there they are transparent. The patches extend out to the nodus of the wing—the little "bend" on the leading edge. Here's another view of this individual:

Other distinctive field marks of this species are the black side stripe on the abdomen, the yellow at the base of the abdomen, and additional yellow on the sides of the thorax.

The female is generally yellowish in color, which is typical in females and young males:

The female also has amber wing patches, like the male, which makes for easy identification.

Band-winged Meadowhawks have noticeable dorsal fovea—the red areas on the top of the eyes.

As can be seen, the eyes are red on top, and yellowish below. The red dorsal fovea are the areas of best vision. When the meadowhawk wants a good view of a prey item or a potential mate flying by, it points the dorsal fovea in that direction.