An attempt is made in this present paper to seek a model which conforms to the econ-ecological principle on the basis of the current control methods. A deterministic static model given in it describes the strategy in the control of the 2nd brood cotton bollworm by use of chemical pesticides in Henshui areas, Heibei Province. Five components are contained in the model, such as the lint economic losses caused by the 2nd and 3rd broods, and the costs of control of the two broods and the midsummer aphis. The ob...