Thursday, 26 October 2017

Chinese Oak Silkmoths

Antheraea pernyi are supposed to be one of the easiest silkmoths to rear, but I have had a few problems with them the past few times I have tried.  I think its because they are intensively reared in sterile conditions, with the use of antibiotics, to produce a type of tussah silk.  The caterpillars don’t develop a very strong immune system when they are raised in these conditions, and if you try to rear them at home, they don’t do very well.  Anyway when I saw some eggs being advertised for sale that were supposed to be from wild stock, I took a chance.  It turned out to be a good move.

The eggs hatched into tiny black caterpillars.  As the name suggests, they like oak.  They much their way through those leaves, shed their skins, carry on eating, and then at the next skin change, they turn bright green. 

They stay bright green for the rest of their life as a caterpillar, but get a lot bigger.  


That green doesn’t look like a great camouflage colour until you see them on some really fresh oak leaves, then you realise that they blend in very well indeed.

Every so often, they go quiet as they build up to shedding their skins.  Their new head grows behind the old one, and to shed their skin, they push off their old face and wriggle and pull themselves out of their old skin, leaving it behind fixed to the branch.  They don’t eat for a little while before shedding, so once they have gone through the process, they are pretty hungry.

Here’s one of my caterpillars just about full size, they really are quite impressive at this stage.  They are eating a lot now, because they won’t eat again once they are ready to spin their cocoons.  They need to consume enough food at this stage to produce silk, to give them the energy to pupate and then to emerge as a moth and survive for a couple of weeks, hopefully long enough to find a mate and produce the next generation.

Its very satisfying when you get to this stage -  freshly spun cocoons  - they are a beautiful pale gold colour and quite substantial.  Inside the caterpillar will shed its skin one final time and turn into a pupae.

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