Our neighbor is a teacher and her class has some silkworm caterpillars that they are going to watch them develop a cocoon and then turn into a moth. She is super sweet and offered to bring us some caterpillars to take care of too. They certainly aren’t the cutest pet I’ve ever had!

The silkworm is the caterpillar of the domesticated silkmoth, Bombyx mori (Latin: “silkworm of the mulberry tree”). They were friendly and didn’t need much work, except that they only eat leaves from a mulberry tree so Stuart soon made friends with another neighbor down the street who has mulberry trees in their front yard. They were fine with him picking leaves for our new friends anytime we needed them. Thank you, sweet neighbors! These little guys eat continuously so we had to get new leaves quite often. The silkworm is entirely dependent on humans for its reproduction and no longer occurs naturally in the wild.

The cocoon is made of a thread of raw silk from 1,000 to 3,000 feet long. About 2,000 to 3,000 cocoons are required to make a pound of silk. Ten unraveled cocoons could theoretically extend vertically to the height of Mount Everest. It’s so hard to believe because they are so small but the threads are very tightly packed in there. The cocoons don’t feel like silk at all but instead seem more like a dense styrofoam packing peanut.

The adult phase of the silkworm, the moth, cannot fly. The silkmoths have a wingspan of about 1 1/2 – 2 inches and a white hairy body.

He’s a sweet but funny looking guy, isn’t he?

While the larvae is still in the cocoon, it releases proteolytic enzymes to make a hole in the cocoon so that it can emerge as a moth. This cuts short the threads of silk which ruins it for silk production. To prevent this, silk harvesters boil the cocoons. The heat kills the silkworms and the water makes the cocoons easier to unravel. Interesting but sad. We decided to cut open one of the cocoons to check it out. How neat!

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