They have been domesticated for thousands of years, they are entirely dependent on humans for survival. They cannot fly, they cannot find their own food, and they are highly susceptible to disease, so proper care is essential.
Here is your comprehensive primer on keeping and breeding silkworms.
1. Setup and Environment Silkworms need a clean, warm, and well-ventilated space.
Enclosure: Use shallow plastic containers (like Tupperware or shoeboxes). Because silkworms are completely domesticated, they rarely try to climb or escape, so you do not even need a lid. If you use a lid, ensure it has plenty of ventilation holes.
Temperature: Keep them between 75°F and 85°F. If your house is colder, you may need a small reptile heating pad placed under one side of the enclosure (never the whole thing, so they can escape the heat if needed).
Sanitation: Wash your hands thoroughly with antibacterial soap before handling them, their food, or their container. Silkworms are extremely prone to bacterial and fungal infections.
2. Diet and Feeding Silkworms are famously picky eaters. They will only eat one of two things:
Mulberry Leaves: This is their natural diet. Leaves must be fresh, free of pesticides, and dry. Never feed them wet leaves, as excess moisture causes fatal bacterial rot in their gut.
Silkworm Chow: If you don't have a mulberry tree, you can buy powdered artificial silkworm chow online. You cook it with water (like making instant gelatin) and let it set in the fridge. Grate or slice thin strips to feed them.
Feeding Schedule: Feed them 1 to 2 times a day. Younger silkworms dry out quickly, so smaller, more frequent feedings are best.
3. Daily Care and The Life Cycle The larval stage lasts about 3 to 4 weeks. During this time, your main job is feeding and cleaning.
Cleaning the Habitat: You must clean their enclosure daily to remove "frass" (poop) and dried-up food. The easiest way is to place a piece of plastic mesh over the worms, put fresh food on top, wait for them to crawl up to the new food, and then move the mesh to a clean container while you wash the old one.
Molting: Silkworms shed their skin four times (these stages are called instars). When they are preparing to molt, they will stop eating and hold their heads up in the air. Do not disturb or move them during this time.
Spinning: When they are fully grown, they will stop eating, shrink slightly, and turn a bit translucent or yellowish. They will begin wandering to find a place to spin. Provide toilet paper tubes or egg cartons for them to anchor their cocoons. Spinning takes about 3 days.
4. Breeding If you want to complete the lifecycle and get eggs, the process is very straightforward once they spin their cocoons.
The Moths: After 2 to 3 weeks in the cocoon, the adult moths will emerge. They cannot fly, and they do not have working mouthparts, so they do not eat or drink. Their only goal in their brief 5-to-10-day lifespan is to reproduce.
Mating: Male moths will flutter their wings excitedly and seek out females (who are larger and generally stationary). Once they connect abdomen to abdomen, they may stay locked together for 12 to 24 hours. Let them be.
Egg Laying: After mating, move the female to a paper towel or coffee filter. She will lay 200 to 500 tiny yellow eggs.
Incubation vs. Diapause: If the eggs are fertile, they will turn dark gray or black within a few days. Yellow eggs that never change color are unfertilized. Most silkworm strains require "diapause" (a winter resting period). To hatch them, you will need to place the eggs in a sealed container in the refrigerator for 2 to 3 months, then bring them back out to room temperature to trigger hatching.