Prehibernal insemination and short dispersal of Ceratina flavipes (Hymenoptera: Anthophidae) in northernmost Japan

Although females of Ceratina flavipes are believed to be inseminated in spring on Honshu Island, Japan, 100% of the females were inseminated before hibernation on Ishikari Coast, northernmost Japan. Because most, if not all, of the males also overwintered with the females, this prehibernal insemination may be a local event. In the hibernal season, females were more frequently alone in nests than males, whereas the sex ratio in their main habitat was almost 1:1, suggesting that prehibernal dispersal is more frequent in females, but that the dispersal distance is shorter than previously reported.