An efficient cost- and labor-saving method is proposed for controlling the population of two kinds or more of different species of insectan pests in a field by means of distributing dispensers of sex pheromone compounds for the respective species of the insects when one of the sex pheromone compounds is an unsaturated C.sub.10 to C.sub.12 alcohol and the other is an unsaturated C.sub.14 to C.sub.20 acetate or aldehyde. When these two classes of the compounds are mixed in such a proportion that the overall solubility paramater .delta. of the mixture is 9.1 to 9.7 and the mixture is contained in a dispenser body made of polyethylene or a copolymer mainly composed of ethylene moiety, the two compounds can be concurrently emitted from the dispenser in the form of vapor each at a controlled rate over a desired length of time.