Friday, May 15, 2009
This lurid dragonfly turned up in the site I collect computer desktop pics from. It was on my computer most of yesterday, I was looking at it trying to work out what the patterns in the wing veins were about. I guess they help the wing pairs peel apart when they are working in a way I now know as "clap and fling". It's fantastic that the blind watchmaker has made something so intricate and perfect.
The dark spot at the wing tips puzzled me too - what could it be for? I imagine the insect can see the spot whirring around, but surely it must have other ways of knowing how its wings are oriented. Another thing that occured to me was that the spot might be used when slowly moving the wings in a mating display perhaps. The final thing I could think of was that they might be tiny weights, no idea why though.
Googling a bit found an academic paper on the mechanics of four winged flight. I'm sad enough to find this really quite quite interesting. Sooooo - I printed it out and read it on the train on the way home from work.
Most people will glance at what their train-neighbours are reading, while carefully trying to appear not to. The younger woman next to me was oafish enough to betray being a bit aghast that someone would be creepy enough to read about insects, erk. It's as if a swarm of the buggers might stream out from the offending printout. I'm old enough to not give a toss what she thought. Personally I would be warier of the lardy middle aged coke-bottle-bottomed glasses guy I saw the other day, completely unashamedly reading a magazine about handguns.
Aaaanyhoo - it turns out that the wing markers are weights - they are called pterostigma and are used for stopping the wing fluttering when gliding.