B. mori Type B
Silkworm flower -- silkworm type B metamorphosis
In 1972, a book which might have been brought by Philipp Franz Balthasar von Siebold from Japan in 1928 was found at the antique book store in New York City. The book was considered to be written at least a thousand years ago. It was all about offerings to the 60th Emperor, DAIGO TENNO. In this book, KAIKO-SOU, also known as B. mori Type B, a silkworm flower, was mentioned in the section about the imperial clothing.
The silkworm flower plant was cultivated by people to produce silk like that found in silkworms. Unlike D. plexippus Type B, it doesn't produce in large quantities of offspring. B. mori Type B cocoons had been cultivated because of its beautiful purple color which was considered to be a noble color during the era-- only an emperor would be allowed such luxuries. B. mori Type B’s cocoon turned out very smooth, tender, and sensitive purple. The silk shined beautifully. No other colored substance was able to match these qualities.
According to the book, the color mirrors the pH of the soil and it works exactly like Hydrangea flowers. Acidic soils result in blue flowers and alkaline soils bring red or pink flowers.
The soil in Japan is mostly acidic and produces reddish pink cocoons. Farmers used fertilizer to adjust the color of cocoons. There were two kinds of fertilizers mentioned in the book. One is a nitrogenous fertilizer which changed its color red to violet. Another was a potassium fertilizer. The less potassium fertilizer used would intensify the red and more made the blue stronger.
The silkworm flower plants would form green buds which would bloom into flowers. These flowers would have a second blooming which formed cocoons. Once the seconding blooming started, the colors of the cocoon would have been fixed and further fertilization would not affect the result. Farmers had to adjust during the first couple of flowers blooming. Farmers could predict the color of cocoon from its flower which would be pare yellow with intense color from red to blue on the base of the petals. The book had a surprisingly scientific analysis of the fertilizers used to yield specific colors. The perfect imperial purple was a very delicate balance.
Another difficulty in cultivating B. mori Type B was catching the moment that B. mori Type B larva can begin to be recognized. It would happen right after the third ecdysis. A sprout that looked like pink fungus would put forth shoots from a half moon shaped bump on its abdomen. B. mori Type B larva cannot remove its skin from the forth ecdysis by themselves because of the sprout and requires human's help. The study says only one out of 15,000 or more regular silkworms turns to type B metamorphosis. It also encouraged farmers to leave some cocoons hatched by a bombyx mori (an adult moth) in spite of the fact that the cocoon’s silk would become broken after their emergence. The reasoning was that the moth from a silkworm flower might have a higher probability to deliver type B larvas.
There have been no more silkworm flowers discovered in 20 century Japan, but very recently in 1998 it was found that this old tradition has been raising in a isolated village in Shanxi, China. Valuable samples were donated to ATBE (the association of type B metamorphosis entomologists), and it will open the new discovery about ecology of a type B metamorphosis of which unknowns still remain secret.