This paper describes the development of low-cost artificial diets for the silkworm using a linear programming method as well as the breeding of polyphagous silkworm races with a high adaptability to the diets. On the basis of the results of nutritional studies, low-cost artificial diets for the silkworm have been developed by applying a linear programming method to the formulation of the composition of artificial diets. In parallel with the development of low-cost artificial diets, studies on the feeding response of the silkworms to the diets and its inheritance have been carried out and polyphagous silkworm races with a high adaptability to the diets have been bred. Development of a new type of silkworm rearing system based on these methods is deemed important.