US Patent 3,488,196, granted 6 January 1970 to Masazumi Niimura, Jiro Kirimura and Noboru Katsuya, describes a method of raising silkworms on an artificial feed. Larvae are fed mulberry leaf material up to the second or third instar, then a feed with 20-60% protein and no mulberry leaf. Four examples with data tables compare larval growth, cocoon weight and cocoon layer weight against mulberry-leaf-only rearing, and the patent ends with four claims and cited references.