Saturday, July 7, 2012

Beauty in the beast!


…..and still the rain comes tumbling down!

But I managed to spend an hour in Walter’s Copse, Newtown, on the way to a meeting in Newport earlier in the week where I had the first of my annual encounters with the creatures I find the scariest!!
Horseflies! I both love ‘em and hate ‘em. I find them fascinating and love finding and studying them, but they scare me when they’re flying around me looking for a nice juicy bit of flesh to land on and burrow in to!

I was photographing a spider when I suddenly noticed a silent grey blob flying around me. I knew what it was straightaway and, on the 3rd pass, managed to capture it with a frenzied sweep of the net!

It’s Haemotopota pluvialis one of the Clegs (I’m amazed that I haven’t come across a certain politician being compared to his namesake!). Even when it’s raining, these blighters are out on the hunt for a blood meal, hence pluvialis!

 This is one of the reasons why I love ‘em. Look at the amazing colours and patterns in the eyes (the photograph doesn't do them justice at all!).

I'm reading John Lister-Kaye's At The Water's Edge. In the preface he observes the beauty of a spider's web and writes: 'Wherever I look in nature I find myself confronted by the paradox of sublime design and grim function, almost as though one is mocking the other - a deadly game, sometimes so violent and brutish that it takes my breath away - the stabbing bill of the heron, the peregrine's dazzling stoop, the otter's underwater grace in pursuit of a fish. And then the beauty floods back in as though some grander plan than evolution fits it all together with added value, that extra aesthetic ingredient, the work of some unnamed genius quite incapable of creating anything shoddy or brash. So I walk, and I watch, and listen, and slowly I learn.'

I’ve been trying to find out why the eyes of these creatures are so dramatic. So far the only information I’ve come across is that paper by Helga Knuttal and Klaus Lunau. As you would expect, it’s in German, though there is an English overview which reads:

Conspicuous, bright colorations of insect compound eyes may be caused by two different
mechanisms resulting in different functions:
1) A thin layer of bright, light scattering pigment inside the pigment cells bordering cornea and crystalline cones may determine the eye’s outer appearance when seen through the transparent dioptric apparatus. The insect’s vision is not influenced by this phenomenon. The cornea transmits light equally well for all wavelengths involved in vision.
2) Interference filters in the cornea cause colourful, metallic reflections. Transmission measurements of single cornea lenses revealed that the interference filters act as colour filters by reducing transmission of light in a small limited waveband. These filters influence vision, because they change the spectral composition of visual stimuli.

If anyone could tell me what that means I’d be really grateful! :-)

3 comments:

  1. Haha Steve, the words were beginning to blur into one long word by the end of that last paragraph - so glad to see your comment at the end!

    A stunning fly! Not one I want to get too close to though :/

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  2. Did you hear the 'whoosh' as it all went right over my head?

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  3. :-) :-) One thing I have noticed about these flies is that they seem to be attracted to dark clothing.....and when you swat them they just keep coming back!!

    Best wishes,

    Steve.

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