In field application, to ensure the quality of pesticides, to meet the rapid growth of BT bacteria temperature conditions, the higher the temperature, the stronger the pathogenicity. To avoid intense daylight, because ultraviolet radiation can cause damage to BT bacteria, it is best to apply medicine after 4 o'clock in the afternoon. In addition, we must pay attention to the life habit and sensitivity of the pests, host crops and environmental conditions and the application of Synergist. For example, the prevention and control of borer borers should be in the egg hatching peak, 2 times-3 times, especially on stem borer, control effect is good. Once borers are eaten into the stems, the control effect is poor. The prevention and control of corn borer must be strictly mastered in the terminal stage of maize, and can receive good results. Prevention and control of Helicoverpa armigera, should be mastered in ovulation Peak 2 days after $number days of drug application, the effect is significant. The masses have Tezuka not to worm, fight eggs do not fight pest control experience. In this way, when the larvae hatch, a bite of the egg shell to eat the pesticide into the belly, soon poisoning death. B2 pesticide residues can generally reach 7 days ~ days. If it rains, the rain will wash away the liquid and should be sprayed again.