Parasitism by an ichneumonid wasp, Bathyplectes sp., on the clover leaf weevil, Hypera punctata, was investigated for over 10 years in the field of the white clover in Tsukuba, Ibaraki Prefecture. The rate of parasitism fluctuated annually, and sometimes reached more than 30%. High rate of parasitism was observed in third and fourth instar larvae of H. punctata; the maximum rate was 42.6%. The trend of annual fluctuation on parasitism since 1996 was similar at two experimental sites, although the maximum rate of parasitism was different between the two experimental sites. This suggests that such an annual trend of parasitism could be commonly observed through the relatively wide area around the study site. Hypera punctata (Curculionidae) : Host Bathyplectes (Ichneumonidae) : Parasite Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Land zones; Palaearctic region; Eurasia; Asia Bathyplectes; Coleopteran hosts; Annual change in parasitism; Hypera punctata; Japan; Honshu, Ibaraki, Tsukuba Hypera punctata; Hymenopteran parasites; Annual change in parasitism; Bathyplectes; Japan; Honshu, Ibaraki, Tsukuba none not entered