The territory of Slovakia faces in recent years the calamity of subcortical insects. In our diploma thesis, we has decided to deal with this issue. In the work we focus on descriptions of species such as Ips typographus and Pityogenes chlacographus. Also, in recent years, we encounter spruce with flat dying forests, made of this tree. In our work we also deal with the reasons that cause this condition. Results, such as individual captures, were obtained within LS Hronec, the characteristics of which are presented in the work. This, aforementioned area, consists predominantly of spruce stands. To a larger extent, the work is dealing with evaluating the activation of sub-insect by means of pheromone traps and their installation in individual stands. Likewise, we also focused on assessing health factors on model areas. Based on the results we'd processed, we suggested recommendations for forestal operations.