The presented diploma thesis is focused on research and evaluation of data about the current occurrence of damaging factors and activation of the woolly beech scale - Cryptococcus fagi on the model territory of the Valaská Belá forest unit. The work is sectioned into several parts. The theoretical part provides basic information about the European beech - Fagus sylvatica, about its geographical extension and the damaging factors of biotic and abiotic origin affecting it. The following part is focused on the characteristic of the model territory from the perspective of its demarcation, geomorphology, and type of soil and also its classification from the vegetative point of view. The last part of the diploma thesis includes an evaluation of the cover quality, the distribution of damaged individuals as well as an evaluation of potential reasons of the occurrence of pests.