The reproductive capacity and host handling behavior of Gryon philippinense (Ashmead), an egg parasitoid of Acanthocoris sordidus Thunberg, were investigated under laboratory conditions. The reproductive capacity was studied at 25.0±1°C, LD 16 : 8. The highest daily average progeny production of the mated G. philippinense was recorded on the first and second days after emergence from the host eggs. The fecundity of 1-d and 2-d-old females of G. philippinense was 48.5% of the total fecundity. The estimated average survival rate of the immature stage of the female G. philippinense was 95.0%. The intrinsic rate of natural increase r_m was 0.174. The females of G. philippinense mostly deposited the male egg in the first host found. After every successful oviposition, the females of G. philippinense marked the parasitized egg.