This experiment was carried out to obtain basic informations on the development in sterile-male technique of rice stem borer. The species considered is Chile suppressalis Walker. Different developmental stages of the insect namely; larval, pupae and adult were irradiated with $Co^{60}$ gamma ray. The results obtained were as follows: 1) A 1:1 sex ratio in the pupal stage was observed. 2) In the pupal stage sub-lethal dosages$(LD_{50})$ were 26 KR and 26.7 KR for female and male, respectively. 3) The total number of egg masses per female increased with the increasing gamma ray dosages and average number of eggs produced per female decreased in the cross between normal female and irradiated male. 4) The sterile dosage $(SD_{90})$ of the gamma ray irradiation showed 23 KR in the male. 5) The pupal stage is most convenient developmental stage for irradiation.