The biology of Casinaria nigripes was studied in Jiangsu and Anhui during 1983~1984. The ichneumonid is an important parasitic wasp on the larvae of Dendrolimus punctaius and is widely distributed in China. The average parasi-tization was 3.4~50.0%, and its highest percentage (23.0%) was oaserved on the third generation of D, punctatus. The ichneumonid has 5 generations a year in Nanjing. It hibernates at the larva stage within the 3~4 instar larvae of the host. The egg-larva stage lasts 28 days and its pupation period varies from 10 to 20 days. The adults copulate and viposit during the day tune. They live for 2.8 to 13.6 days and have not phototaxis. The average number of eggs in ovaries of one female was 67-207. The hyperparasites from the coeoon-pupas of C. nigripes have 8 species. The average ratio of hypcrparasitism was 27.9%, 29.5% being the highest in overwintering. Of the 8 species, Brachymeria sectinda-ria was the most important.