A large area of forest pests and diseases occurred in a mountainous area  When discussing the use of pesticides, Lao Xu proposed: Either use chemical pesticides such as methamidophos, or use biological pesticides  The former has been used in the past, is cheap, has good insecticidal effects, but is highly toxic; the latter has never been used
The effect is uncertain and the price is expensive
Chemical pesticides are better than biological pesticides and should be given priority.