I just joined my guild's weaving study group and at a recent meeting, one member gave us a demo on silk reeling. She brought some silkworm cocoons and equipment showed us how the silk strands can be pulled off the cocoon and made into fiber.
First, the cocoons are warming in water in a crock pot and the micro strands are loosened with the help of a fork.
Then they are joined up in a bundle of about 10-12 strands and held in place with a metal loop, then looped around the reel.
The reel then goes round and round, taking up the bundle of silk strands. You just keep going until your little cocoons are completely unwound, leaving the poor naked, dead worm ! The fibers still have a coating on them so need to be cleaned or de-glazed if you want to spin them into a soft silk yarn, otherwise they will be rather stiff. This fiber is what it s used for silk organza fabric.
You can also take the cocoon and pull in underwater into a silk "napkin" to be used into felting or other process.