The chromosomes of three Japanese weevil species, two parthenogenetic and one bisexual, are described for the-first time. Males of the alate Cyrtepistomus castaneus are unknown. Oogonial metaphases had standard, 3x = 30, and substandard, 3x = 31, chromosome numbers (range ca. 28 — ca. 33). No reduction occurs at meiosis (ca. 30 univalents at MI). This species is therefore considered to be a triploid parthenote. Eight oocyte metaphases of Blosyrus japonicus, which also appears to lack males, showed between 66 and 61 (or 60) univalent chromosomes (two had 66, three had 65). These counts categorize the mothers as thelytokous hexaploids, a degree of polyploidy not previously found in the Curculionidae. The male of the bisexual Ceuthorrhynchus lewisi (2n = 28) possesses an unusually large pair of sex chromosomes. The metacentric X and telocentric Y form an achiasmate, umbrella-like bivalent that is unique among known Coleoptera.