Studies were conducted at the Pakistan Forest Institute Peshawar to find out the effect of duration of mating on the fecundity and fertility of eggs of two strains of silkworm, Bombyx mori L. Out of 6 mating durations from 1 to 6 hours, 5 hours duration was found for the maximum fecundity and 1 hour duration for the maximum fertility of eggs of Chinese and Japanese silkworm strains. Since mating durations from 1 to 6 hours are statistically non-significant therefore, 1 hour mating duration can be used for the maximum fecundity and the maximum fertility of eggs.

Key word: Mating duration, Fecundity, Fertility, Silkworm.