Thursday, 2 August 2012

Silk Moth Breeding Continued

You can see here how the moth climbs up on the Buckminster Fuller-like paper cut out after they break out of their chrysalis.  This one is a male. His antennae are bigger than the females'. They look a  little maniacal.

I suppose they thing on their minds.

I used to breed and cross breed four kinds of ancient breeds of silkworms. Aojuku青塾, Koishimaru小石丸, Tanegashima 種子島, Tenryuseihaku天龍清白 with a very good Chinese cocoon, Shi no 21. It was quite a feat to breed the parent stock and keep them going pure-blooded and cross-breed the others for research purposes and keep it all organized. Not because the silkworms can walk into another's territory but because the different silkworms mature at different rates and the moths do not emerge on the same day to breed. By checking out the chrysalis each day you can see how they are maturing. I would put the early birds into the fridge to slow them down so the late breeds could catch up. I noticed that putting them in the fridge just before the moth emerges is not a good idea. (It can't be helped when something comes up like sudden urge to climb Mt Fuji.) The moths looks a  little worse the wear and tear it seems.
I  put the chrysalis in the refrigerator for four days while I went to Mt Fuji they did come out looking a tad mottled but perfectly healthy. 
You can see the facial features and wings of the about to emerge moth  on the chrysalis. And in the picture above it, the empty chrysalis. 

You introduce one male to one female. Sometimes they can't manage to do it as one of their rear ends were unintentionally smushed being bounced around inside the cocoon. Unfortunately they are rejects. 
When breeding hundreds of moths it is hard to deal with all the moth wing dust and the logistics of disposal, so I would prepare a bowl of water with a big squeeze of dish detergent and put the finished moths in that. The dish detergent makes their wings heavy and they drown quickly. 

Poor things. 

I am just breeding a few dozen these days so I can take the used males and females who have finished laying eggs and put them in the grass up on the mountain behind the house. They have no mouths to eat and can't fly or really walk much. Birds pick them off quickly or they die in a few days naturally. In Laos they mush the moths up and add fish sauce and eat them.

The students yesterday found this all amazing and moth breeding took precedence over the indigo vat.
The males are much smaller. The females are full of eggs.

You let them have fun for a few hours in a dark place and then it is time to break up the party. You separate the them with a little tug. Males can be used twice without much of a break if necessary.  The females are placed on a sturdy piece of pH neutral paper, a cap placed over them (to ensure the eggs are laid in one spot and easy to count) and put in a quiet dark place. Usually they will start laying eggs right away and will finish in a few hours.  Then the moth is disposed of as you like. Abandoned, killed or eaten.....wonderful options.

The fertilized eggs will start to turn color within twenty-four hours. If they stay beige it means they were not fertilized. The eggs on the right were freshly laid and will go through a strange and beautiful color metamorphosis for the next three days. 

I write the date they were laid and the variety of silkworm on the paper. There are between 350 and 500 eggs in one ring.  One kimono needs 2500 silkworms, six moths worth of cocoons. If the eggs are laid in spring they will hatch again a few weeks later. Timing the eggs to hatch is another blog.  Air pressure shock, electric shock, light flashes, false refrigerated winters or hydrochloric acid baths are all techniques used to time hatching. I went to the Tokyo Agricultural University for a few days many years back and learned how to use the 80 degree hydrochloric acid baths to shock the eggs and start the cells dividing so the eggs hatch ten days later.

It is important to calculate the amount of available mulberry leaf when deciding the amount of silkworms you want to rear.

There are so many little details to add to this process. If you have problems or need some more detailed information just ask. I've been doing this several times a year for 15 years now and pretty much have encountered every problem and know how keep the process organized and efficient. Cross breeding is interesting and introducing new genetic stock is always important.


  1. ...fantastic, no wonder your students are fascinated. the pictures are great. not sure I want to eat at your house!

  2. I choked down the moth mush once in Laos. Don't think I would serve it up at home. I did tempura moth chrysalis' once and served them. Japanese are so polite they actually ate them!