Most of the moths laid diapause eggs if their embryos were incubated under the conditions of 18°C and darkness and fed their larvae on artificial diet without any mulberry leaf-powder after hatching under the conditions of 25°C and 16 L hours of day-length, but laid non-diapause eggs by the most of moths if larvae fed on the different diet with mulberry leaf-powder as can be seen in Fig. 1 (a) . It was then suggested that the mechanism determining the diapause direction is not depending directly on the chemical conditions; absence or presence of mulberry leaf-powder in the artificial diet, but those characteristics determining the utilization of food materials for diapause direction are depending on the acquired constitution of larvae themselves persisted in some latent processes from their latter stage of embryonic period.
On the other hand, all of the moths laid nondiapause eggs if the same larvae fed on artificial diet without mulberry leaf-powder as described above were subjected to the different conditions of 20L hours of day-length during the whole larval period as can be seen in Fig. 1 (b) . Those reversed results in diapause direction are suggesting that the temperature-photosensitive mechanism to control diapause direction is provided not only in the embryonic period but in the larval period of bivoltine hybrid between Gunshu and Shugetsu in silkworm Bombyx mori.