Between 1995 and 1998 we made trapping and follow up the evolution of benificials in nine Citrus fields located in Castellon and Valencia provinces. Our goal was determine the seasonal evolution of their populations. Sticky and chromatic traps were used for trapping. In general, we have noticed that the maximum level of beneficials takes place between May and October, and a summer population decrease occurs only for a few species. Among parasitoids Braconidae and Aphelinus spp., present their highest populations during the spring as well as Aphytis spp., and this last genus is abundant also during Summer and Autumn. Signoforidae are at their highest level in summer, and Cales noacki (Howard) and Eretmocerus spp. in summer and autumn; captures of Metaphycus spp. occurred during the whole year. Among the depredators, Scymnus spp. increase its presence in March, and remain stable until September. The highest population of Conwentzia psociformis (Curtis) happens during Spring and autumn. Populations of Chrysopidae, Rodolia cardinalis (Muls) and Aphidoletes aphidimyza (Rondani) increase in June and maintain their population levels until August for the two first ones and until October for the third one. At the same time, we have also studied the pests evolution comparing it with the seasonal evolution of the beneficials. In general, a decrease of the pest pest population is related with an increase of the beneficials. none