Substances in Mulberry Leaves which attract Silkworm Larvæ (Bombyx mori)

Abstract

ALTHOUGH the larvæ of silkworms eat a few kinds of leaves other than mulberry leaves, for example, fig and lettuce, these do not support normal growth. Proteins and carbohydrates are necessary food substances, but are incapable of acting as attractants, since they are odourless. Experiments showed that mulberry leaves placed within 3–4 cm. of silkworm larvæ did attract them. An investigation was carried out on thirty-eight species of leaves as to the chemotaxis of silkworm larvæ¹. It was found that substances which attract silkworm larvæ exist widely in green plants, but that the degree of attractivity differs. The leaves of soya bean, mulberry and tea had the strongest attractivity, but the silkworm larvæ gathered around them without eating them. On the other hand, silkworms exhibited a weak chemotaxis to the leaves of fig and lettuce, but ate them when hungry.