The biology of Casinaria nigripes, an important parasitoid of the forest pest Dendrolimus punctatus in China, was studied in Jiangsu and Anhui in 1983-84. Parasitism averaged 3.4-50% and was highest (23.6%) in the 3rd generation of the host. The ichneumonid had 5 generations a year in Nanjing and overwintered in the larval stage in the 3rd-4th larval instar of the host. The egg-larval stage lasted 28 days and the pupal stage 10-20 days. Adults mated and oviposited by day and were not phototactic. The numbers of eggs in the ovaries averaged 67-207/female. Eight species of hyperparasitoids caused 27.9% parasitism; hyperparasitism was highest (29.5%) during over-wintering. Brachynieria secundaria %%-as the most important hyperparasitoid. none