Submitted thesis deals with issue of bark beetle and impact of pheromone trap on forest stand border. Our observation was placed in area admistrated by forest management of Oravska Polhora. On this area spruce-based monoculture markedly dominates, hence is issue of these pests very actual. Our goal was to find out the optimal distance between the pheromone trap and the forest stand border, so that the trees in forest stand border were attacked by bark beetle at least. We assumed that the closer the pheromone traps are placed to forest stand border, the more bark beetle will occur in forest stand border. By comparing the observated trees results in forest stand border, we found out that the critical border of ten metres should not be crossed. The pheromone traps installed in longer distance have no impact on forest stand border, however their monitoring accuracy is also doubt.