A procedure for the fight against the infestation of honey producing bee colonies is described, especially the varroosis, consisting of the introduction into the beehives of a composition with an aqueous, pasty character containing microcapsules of a polymeric coacervate which include microdroplets of essential oils, especially thymol. The procedure allows the beehive to be treated by only one introduction of the compound, assuring effective levels of essential oil in the atmosphere of the beehive during four to six weeks, all this without producing rejection effects in the bee colony.