Considerations
Though they can be bought as eggs or as live worms, buying bulk fertile eggs and hatching them yourself is the cheapest method. Fertile silkworm eggs are packaged in bulk lots of several hundred. Silkworm cocoons from which the moths have already hatched are also available.
Why Buy Silkworms?
Silkworms are in demand not only for the silk cocoons they manufacture, but also as live feed for fish, geckos and other pets. If you are buying them for fish food, buy the eggs and raise them yourself. The hatched silkworms can grow to be up to three inches in size and are a better, cheaper source of nutrition than, say, crickets (see Resources).
Varieties
If you are breeding silkworms, zebra silkworms are best for cocoons and for tracking silkworm gender.
School Projects
If you are buying silkworm eggs for a school project, Mulberry Farms sells a silkworm kit that includes 20 to 25 large silkworms or 50 small silkworms, prepacked with their food in a growing cup (see Resources).
Silkworm Supplies
The same vendors who sell the worms also often sell food (mulberry leaves), silkworm cups and tanks, and remedies for preventing illness in silkworms, such as molds or mites.