Studies on the monitoring of the most damaging defoliant species of oaks (Lymantria dispar and Totrix viridana) through pheromone traps in forest ecosystems are some of the rare achievements in this field, for our country. It has been shown that during the vegetation season there is an alternation of defoliant species, with the presence and development of the II generations, harmful to the foliar limb (the quantity of pests being higher during the first generations and reduced in the second generation). The activity of phytophagus insects was directly influenced by the climatic conditions in the studied areas, the presence of the nutrition source - oaks and the presence of the infestation source. Based on the evidence of males captured in the pheromone traps, digital maps of the spatial distribution of the imago of studied species were developed, which allowed the determination of the position, the direction of spreading and the size of the pests (the necessary studies in sustainable forest management).