Wednesday, March 04, 2009

Silk worms at 9 days old.

At first glance they look like cinders. They have the same greyness against the barely-green feed. Before they move they look a little like the remains of twigs, or maybe the fossilised remnants of coral or brachiopods. It takes a short time for my eyes to adjust. It is like looking into the dark. Then, perhaps in response to the lid coming off and a short rush of cool clean air, they stir a little. Some are like cobras; they lift the swelled and slightly flattened head-ends of their thoraxes, and sway before me. Only then does my eye truly fasten upon them and I can see them.

Silkworms with scale at 1 cm intervals

They are about a centimetre long now and their bodies have filled out a little more so they look like real caterpillars. It is becoming easier to distinguish them. There are different colours and different markings. Some are a pale brown, but the rest are varying shades of grey. Some don't move at all, and on closer inspection these immobile silk worms are clearly moulted skin. Perhaps they are the first moult. However it is difficult to see which have moulted and which have not because there is no dramatic change in appearance.

Silkworm with moulted skins

I read somewhere that they only make silk in their last instar, but maybe that should read they only make copious amounts of silk in their last instar. The silk glands are clearly there from the start because apart from the fine mat of silk that soon coats their food, they dangle from my tweezers like a spider when I try to clear out their box. But whereas such a captured spider would frantically spool out more silk and escape, the silkworm is more nonchalant. It doesn't struggle. In fact it barely moves. Instead it seems to wait patiently (or mindlessly) to be placed somewhere else. After all, a silkworm is close to being a manufactured animal. For years they have been bred in captivity and cannot exist in the wild. They exist because men have made them so. It is as though they passively accept their lot, ponder over us a short while with their raised heads, and then continue grazing.

Silk coating food

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Blogger Debra Hamel said...

They don't exist in the wild anywhere?

Thu Mar 05, 04:26:00 am  
Blogger Clare Dudman said...

No, amazing isn't it? There are 'wild' silkworms but they are a different species the saturndae ( think) and their silk is inferior in some ways, for instance it is often coloured, uneven and more resistant to dyeing. The bombyx only survives in cultivation - I suppose it has been weakened by cativity, maybe deliberately so. The moth cannot fly and the caterpillars are easy to contain in a tray.

Thu Mar 05, 07:01:00 am  
Blogger Debra Hamel said...

Okay, so this type was bred in captivity originally and never existed in the wild. I guess you can't just let them loose in your yard, then.

Thu Mar 05, 12:35:00 pm  
Blogger jem said...

It's clearly a love hate relationship I have with your silkies. I love the nonchalance, that's an attitude I'm admire - but the image of them as mini cobras chills me. That's one snake I've always been very wary of. Something about it's ability to be vertical is just wrong!

Sun Mar 08, 10:56:00 am  
Blogger Clare Dudman said...

Mainly I love them, Jem. I agree that a cobra does feel menacing, so for that reason maybe it is not the best description - maybe meercats, sniffing the air (although I think they are mainly poised there to gather their strength to moult).

Sun Mar 08, 01:14:00 pm  

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