The functional responses of Trichogramma chilonis and T. ostriniae were investigated by offering the eggs of Ephestia kuehniella and Plutella xylostella as host. The results are summarized as follows: 1. The percentage parasitism by each parasitoid increased as the host density increased, then reached to the maximum, as thereafter decreased. 2. The sex ratio of female progeny of each parasitoid ranged from 0.64 to 0.92 in all host densities. 3. No significant difference in the functional response of T. ostriniae to host densities was observed according to host species.