Pyriproxyfen is a novel kind of insect growth regulator, It has the same effect on the insect as juvenile hormone and has various kinds of effects such as inhibiting the mosquitoes, pupating of the flies larvae and its feathering. Upon being exposed to this drug agent, the larvae of mosquitoes and flies will mostly die in the pupal stage without being able to get into feathering. The duration of this agent will persist up to a month or so. Moreover, it is convenient for using with no odor and is a good kind of drugs for killing of mosquito and fly.