Tuesday, 13 February 2007

Dragonfly

It was hot and humid yesterday. I'd spent the day in a conference centre where the air-conditioning had been turned up to 11, so walking out into the late afternoon sun was a hell of a shock. By the time I got home (in a car with no cooling), I was ready to crawl into the refrigerator. But first I had to do the rounds of the garden.

Despite (or perhaps because of) the heat, most plants are doing well. Only the Alyogyne huegelli is suffering but I'm hoping that it will come good once it settles in to its new spot. And the plants have brought in the insects. There are flies and hoverflies, bees and wasps, bugs and beetles, moths and butterflies, damselflies and dragonflies. No matter how bad the day has been, it's difficult to resist the magic of these exquisite animals. (Having said that, it takes no effort to resist the magic of cockroaches, silverfish and those bloody meal moths.)

This dragonfly posed obligingly on the Livistona decipiens*. Having taken a bunch of portrait shots, I thought I'd try to identify it. Not that I know much about dragonflies but I've bought a bunch of books written by those who do. I thought I'd try to key out this orange beauty.

I knew it was a dragonfly and not a damselfly. The eyes of dragonflies are usually close together (but not shifty) and the fore wings differ in shape from the hind wings. Damselfly eyes are more widely spaced and the two pairs of wings more or less identical. (The normal caveat applies, though—there are exceptions.)

But the diagnostic features of dragonflies — those that distinguish one species from another—are almost all on the wings. And it's not until you start looking at them that you realise just how extraordinarily complex those wings are. And how much you can't see in a photograph.

I followed the key through characteristics of the antenodal crossveins, the orientation of the arculus in relation to the basal side of the hind wing triangle and the shape of the anal loop. (Don't ask.) And I think my visitor is a wandering glider or global skimmer (Pantala flavescens)**.

This species is found throughout the warmer regions of the world. It even occurs on Easter Island. Jill Silsby mentions that it was one of the first insects to recolonise Bikini Atoll after the atomic tests. That's a dragonfly that gets around.
_____

* A cabbage palm from the Rockhampton area in mid-east Queensland. It absolutely loves this weather.

** Can any odonatologist confirm this ID? Or tell me that I can't follow a dichotomous key to save my life?


Read more
Silsby, J. (2001) Dragonflies of the world. CSIRO Publishing, Collingwood.

Theischinger, G. & Hawking, J.H. (2003). Dragonflies of Victoria. CRC for Freshwater Ecology, Albury.

Theischinger, G. & Hawking, J.H. (2006). The complete field guide to dragonflies of Australia. CSIRO Publishing, Collingwood.

6 comments:

Duncan said...

Lovely shots Snail, wish I could get some like that, they won't sit still for me. :-(

Snail said...

Note that this is the only dragonfly shot in 6 months! It's the camera, I reckon. Same as the skippers.

(Actually, there is another dragonfly shot, which I must put up. It's a classic point and shoot. The day was so bright that I couldn't see what the camera was focussing on. Just happened to be a side on shot of a airborne dragonfly. I'll put it up tomorrow.)

Shorty CreeKI said...

Hello snail and duncan,
We have a (now almost dry) creek running through our backyard in the Adelaide Hills.

The most interesting natural history learning for me in this yard to date has been learning the dragonflies' "road maps".

Each day I find that if I spot a dragonfly and watch it for at least 10 minutes, it will eventually follow a pattern, as if there is an invisible road map.

Although the path in the air is extremely erratic, there do appear to be three or four resting spots and at least one of them will be used over many circuits, for a minute or so at a time.

I have even got a photograph of one, not up to DO's or Tapper's standards, but getting better all the time.

By contrast, the dragonflies I tracked on Shorty Creek, Kangaroo Island, did NOT follow that kind of path, which was disappointing because I did have all day ... and they were quite different; a gorgeous blue.

jj

Snail said...

The ones that wander into my garden aren't so predictable, but that's presumably because there's no water to patrol. Nice seeing them, though. Serendipity at its most ... um ... seredipitous.

Shorty CreeKI said...

:)



goodnight snail and lurkers.

*tap tap and away* as the saying goes.

tapperboy said...

!

:)

:)

tap tap and away

:)