Sunday, 26 August 2007

Atlas Moth

This morning, I had a much more welcome insect visitor to the house than the usual mosquitoes, coconut beetles, and the 'mad bomber' May beetles,which fly, at great speed, and very noisily, from one vertical surface to another, knocking themselves out as they do so.

It's an Atlas moth, of the saturnid group, and is gigantic; you can see from my photo just how large and beautiful it is.

I don't know the exact species; the Wikipedia page shows another species as Attacus atlas, but at the foot of the page, quite a few photos of another moth, identical to this one.

But it does mention that in Canton, the local name is Snake's Head Moth, and perhaps you can see why. You can see a definite snake image at either side of each wing, glaring fiercely to left and right.

As it happened by lucky coincidence, I was, just last night, idly browsing through:
In the Blink of an Eye: How Vision Kick-started the Big Bang of Evolution - by Andrew Parker (no relation), where he discusses the snake's head.

He says that ultra-violet light, particularly strong in mid-day sunshine, when moth-eating birds are around, actually intensifes the snake's head image at the expense of the other wing-pattern elements, which really come into their own as protective camouflage in other lighting conditions.

Many birds and insects can perceive ultra-violet light reflections, which we can't, quite so well. Many flowers, that look dull to us, show an ultra-violet light patterning that is positively like a reflective direction sign to a nectar-seeking bee.

In other words, this moth has actually evolved mimicry of an attacking snake for some light conditions, and mimicry of an bit of old tree bark or forest floor for others, which is quite a subtle and wondrous thing to do.

The other wondrous thing about this moth is that it has no mouth parts, so cannot eat anything at all during its adult life. It survives, for about two weeks, entirely on its puppy fat, while it flies gracefully around the forest, looking for a mate before it dies.

Makes you wonder, doesn't it, if the adult moth is the 'real' animal, or if the caterpillar, which is itself quite remarkable, is the 'real thing'.

No comments: