Using the bivoltine silkworm race (Hosho), we investigated the effect of light of different wavelengths during larval rearing on diapause in the next generation. The larvae hatched from eggs that had been incubated at 25°C, 24L were reared on the artificial diet containing 50% mulberry leaf powder under the long day condition (24L and 20L4D) .
We found that light in wavelengths from 400 nm to 540 nm affected the production of nondiapause eggs, and that the 20L4D light group produced more nondiapause eggs than the 24L light group. Moths that emerged early tended to produce nondiapause eggs, but when the larvae were reared on fresh mulberry leaves, nondiapause eggs were not produced under any light condition.