Abstract: Eight populations of Trichogramma dendrolimi were collected from De ndrolimus superans,D.tabulaeformis,D.spectabilis,D.punctata and D.kikuchii in 8 provinces or municipality of China.They were propagated with eggs of Co rcyra cephalonica in a rearing room of constant temperature and humidity with 14 hours photophase.Both parental and filial generations were examined for morph ological diagnosis.Structures of the male genitalia of the 8 populations were fo und identical.Yet the populations could be divided into three rather distinctive groups according to the ratio of the length of flagellum setae over the width o f antenna flagellum.The differentiation among the three groups appeared to be ge ological.The populations from Beijing and Inner Mongolia,which are in high latit ude,had long setae,those from Yunnan and Hunan Provinces,in low latitude,had sho rt setae;while the remaining four populations had medium length setae were from Guangxi,Shandong,Zhejiang and Jilin Provinces.ANOVA and Ducan′s test were used in data analysis.