Phenolic compounds are important in several respects during the development of Bombyx mori. Apart from acting as biting factors, morin and chlorogenic acid enhance the rate of development, especially in the early stages. This is also true of vanillin. Because of this, phenolic compounds are used in the synthetic diet of young larvae. The oxidised products of phenolic compounds are often harmful to silkworms: whether the reduced forms are metabolised is unknown.Since Hamamura (1959) ascertained that the feeding mechanism of the silkworm, Bombyx mori, depends on three factors, an attractant (volatile alcoholic substance), a biting factor (13-sitosterol and isoquercitrin), and a swallowing factor (cellulose), studies of biting factors have been emphasized.Hamamura et al. (1962) found that morin ( Fig.