Abstract: This paper deals with the control threshold of Ceracris kiangsu Tsai(CKT), a serious pest of Phyllostachys heterocycla var, pubescens(Mazel) Ohwi(PHPO), which is widely planted as an important economic tree in the south China.The leaf number and quantity of PHPO in different breast diameters and different life stages and the feeding quantity of CKT in one generation and different life stages was studied. The damage of CKT to PHPO was tested. Based on the oringinal data and the control economic factors, the control threshold of CKT was established. The main result was as follows, when defoliated rate of PHPO reach 10%, the damage of the growth and development of PHPO would take place, so when the density of CKT population reached that level, which could cause 10% lost of PHPO leaves, then the control to CKT was necessary. The CKT density that cause 10% lost of PHPO leaf can be calculated out according to the technique introduced in this paper, which coneides bamboo grove appearance, CKT quantity per m² or per individual bamboo tree and the investigation time to CKT respectively.

Key words: Control thresholdv ^{Ceracris kiangsu} Tsai, ^{Phllostachys heterocycla} var. ^pubescens(Mazel) Ohwi