The parasitoid community associated with the monophagous leafroller Eudemis gyrotis (Meyrick) (Tortricidae) on a bayberry, Myrica rubra Sieb. et Zucc. (Myricaceae) was studied in a natural population at Mt. Tanakami, Shiga, central Japan, in 1998 and 1999. The parasitoid community structure of E. gyrotis was described in order to elucidate the effect of the ecological features of parasitoids on the community organization. The seasonal changes in the number of E. gyrotis larvae plus pupae showed a similar pattern between 1998 and 1999. Thirteen species of parasitoids were recorded as primary parasitoids of E. gyrotis, and ten as secondary parasitoids. Apanteles sp. (ater-group) (Braconidae) and Goniozus japonicus Ashmead (Bethylidae) were dominant larval parasitoids. Apanteles sp., which is a koinobiont endoparasitoid, laid an egg on an early instar larva of E. gyrotis and emerged from the fourth instar larva. On the contrary, G. japonicus, which is an idiobiont ectoparasitoid, laid eggs on the fifth instar larvae of E. gyrotis more frequently than on the third and fourth instar larvae. Moreover, the sex ratio of the G. japonicus offspring was female-biased. The three species of primary idiobiont endoparasitoid, Brachymeria excarinata Gahan (Chalcididae), B. lasus (Walker), and Itoplectis alternans spectabilis (Matsumura) (Ichneumonidae), attacked the pupa of E. gyrotis. The lack of discrimination ability in the three species of the parasitoids between the parasitized and unparasitized hosts may result in inter- and intra-specific competition among the pupal primary parasitoids. none