Thursday, October 30, 2014

Domesticated silkmoth

Meet the domesticated silkmoth (Bombyx mori) better known in its caterpillar state in which it is called silkworm though it’s not a worm at all. This species is an economically important insect, having been domesticated in China from its wild ancestor Bombyx mandarina about 5000 years ago. The adults have actually lost the ability to fly and also lack fear of potential predators. These changes have made the species entirely dependent upon humans for survival and it no longer occurs naturally in the wild.

What makes them so valuable is silk. After they have molted four times the larvae will enter the pupa phase of their life cycle and enclose themselves in a cocoon made up of raw silk produced by the salivary glands or to be more precise - a 900m long single strand of silk. The cocoon provides a protection during the vulnerable, almost motionless pupal state. 

About 3,000 cocoons are required to make half a kilogram of silk. At least 40 million kilograms of raw silk are produced each year, requiring nearly 5 billion kilograms of cocoons.

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