Abstract: Egg-laying habit, gall-making ability, larval behaviour and species quantitative dynamics of the eurytomid wasp, Aiolomorphous rhopaloides and the torymid, Diomorus aiolomorphi,were observed for identifing the interspecific relationship of the two species.A. rhopaloides lays eggs in newly-sprouted buds and a gall develops at the site of egg-laying as the bud develops into a new branchlet.D. aiolomorphi lays eggs in the young gall developed by A. rhopaloides and its larvae kill the eurytomid larvae,occupy the gall and feed on the internal tissue before maturing. It is suggested,based on the results,that the torymid,instead of a pest insect of bamboo,can be regarded as a natural enerny of A. rhopaloides.