How to Breed Silkworms

How to Breed Silkworms

Breeding silkworms means letting some of the batch pupate instead of feeding them out, then collecting the eggs the moths lay. The mechanics are simple; the hard part is that you need a steady mulberry supply for the generation that follows.

Letting Them Pupate

At the end of the fifth instar a silkworm stops eating and looks for somewhere to spin. Move those worms to a pupating container lined with paper or mesh — they need something to anchor silk to. Kitchen roll, egg-crate cardboard or a mesh screen all work.

Once the cocoon is spun, leave it alone.

Cocoon to Moth

Moths emerge in 10 to 14 days. They are not the animal most people expect: adult Bombyx mori are the product of five thousand years of domestication and are entirely dependent on us. They do not feed, and they do not fly. Their only job is to mate and lay.

This is the same fact behind the species' strangest feature — silkworms cannot survive in the wild at all. There is no wild population to return to.

Mating and Eggs

Pair the moths and leave them undisturbed. Females lay their eggs on whatever surface they are on, which is why a paper lining is worth having — you can lift the whole sheet out rather than trying to move eggs individually.

Storing the Next Generation

Harvest the eggs and hold them at a steady 50–60°F until you want them. That is what turns breeding from a continuous chore into something you schedule — see how to hatch silkworm eggs for starting them again.

The Honest Constraint

Silkworms eat mulberry and essentially nothing else. Breeding them commits you to a mulberry supply — a tree, or a reliable source of chow — for every generation. Most keepers find buying worms in batches cheaper and far less work than maintaining that supply, and there is no shame in that being the answer.

More in the complete silkworm raising and care guide.