Friday, July 3, 2009

Anything with wings.

Another hot, dry day. The birds are up to nothing, the gardens aren't providing anything new, which means it's time to head to the pond and look for....

Four-spotted Skimmer, Libellula quadrimaculata.

dragonflies. Dragonflies are mid-summer methadone for jonesing birders. There are usually just enough species around to keep that part of the brain satisfied. I saw four species at Garden City Park today. Number one, above, is the Four-spotted Skimmer. It is most common in/around acidic waters, which is why it is a common species here in Richmond, with our Sphagnum peat-bog soil. Note the dark spot at the midpoint of the forewings, and the faint golden wash along the leading edges of the wings.


Eight-spotted Skimmer, Libellula forensis.

The Eight-spotted Skimmer is a flashy species with two large irregular dark spots on each wing. It is a slightly pruinescent species:

From Wikipedia: Pruinescence, or pruinosity, is a "bloom" caused by pigment on top of an insect's cuticle that covers up the underlying coloration, giving a dusty or frosted appearance.

Pruinescence occurs in many odonates (damselflies and dragonflies). Within the dragonflies it is commonly found in the skimmers (Libellulidae). Typically, only males pruinesce.


Common Whitetail, Libellula lydia (Plathemis lydia in some sources).

The Common Whitetail shows a higher degree of pruinescence. This species prefers unglamorous spots--muddy water, puddles, cattle ponds and often perches on the ground. Quite the slummer. Males raise their conspicuous abdomens to threaten rivals, so a low perch would seem appropriate.


Blue Dasher, Pachydiplax longipennis.

Finally, the Blue Dasher, also a libellulid, whose mature males have bright green eyes and a slightly pruinescent (blue) thorax and abdomen. It is relatively small compared to the species above, and perches on twigs or stems with its wings cocked forward. Dragonflies, like most birds, are reliably stereotypical and restricted in their behaviours.

There, I've had my fix. I feel better now.


Reference:

Cannings, R.A. 2002. Introducing the Dragonflies of British Columbia and the Yukon. Royal British Columbia Museum. 96 pp.

3 comments:

randomtruth said...

Woohoo - dragonflies! Love them Top Guns. Jewels on wings they are. I thoroughly enjoy trying to get good shots of all the different species that zip around the farm pond at my bro's place by Yosemite. Hoping to head up to see some soon in fact.

Thanks for the preview!

-Ken

Hugh said...

They are a lot of fun once you become attuned to them. They were background to me for the longest time--until a topnotch conservation biologist shamed me into stopping and looking at them.

spinyurchin said...

Nice shots.
And I am enjoying my new word, 'pruinescence'.
Pruiiiiinnnnescence.