Abstract: Six generations of C._ sinica could be reared outdoors in a year in the BeiJing auburba. Observations made during 1980 to 1983 showed that C, sinica overwinters aa adult from late September to mid March mainly in rock crevices and debria in the mountainous region. In spring, the population remained low in the plain agricultural area until July and August, when two adult peaks occurred respectively. Adult population declined drsmaticly after September, resulting from harvesting of field crops. Conseqently, the adults dispersed to and formed a distinctive peak in the mountainous region, where food source and shelters of C. ainica are more adequate than that In the plain. Another adult peak in the area was observed in late spring. It is hence believed that the mountainous region serves aa a reservoir of C. ainica during winter and the source of the initiating population in the plain for the following year. High adult mortality during the overwintering period appeared to be mainly responsible for the low spring population level in the plain area. Manipulation of cropping systems and inoculative releases of C, ainica ara recommended to enhance the predator's population in the early aeason.