In this paper, we describe a hybrid dynamical model incorporating residual and delayed effects of pesticides and pest resistance to simulate the process of integrated pest management. It assumes that spraying pesticides is more frequently used than releasing natural enemies. The threshold condition for pest-eradication is given. Combined with numerical simulations, the effects of chemical control factors on the threshold are discussed. The results confirm that it is not that the more frequently the pesticides are sprayed and the stronger effects the pesticides have on pests, the smaller the threshold is. Further, we give three different control strategies, including switching pesticide strategy and strategy for releasing natural enemies elastically for the pest-eradication, and the state feedback strategy for controlling pests not exceeding the economic injury level (EIL). The results indicate that if the purpose is to prevent the density of pest population from increasing to the EIL, from an ecological and economic perspective, it is not that the more natural enemies are released, and the better results are obtained.