The Mediterranean fruit fly Ceratitis capitata Wiedemann is a very important pest of fruit crops. Originally from the African continent, it is now distributed worldwide and causes great losses in the quantity and quality of fruit, making its trade difficult or impossible. One form of pest control is the so-called “sterile insect technique”, which is widely used because it is environmentally friendly. The introduction of sterilized insects into the agricultural system seeks to reduce the pest’s reproduction rate with the consequent decrease in population size. The mathematical modelling of this problem is presented in this paper in three stages. First is proposed for the state of the pest in the absence of control. In a second stage an empirical rule is introduced and consecuently the model obtained is a theoretical-empirical hybrid wich is simpler than the original having two differential equations: one for the female’s growth rate and the other for the male’s growth rate. In last stage, control by the sterile insects is included.