Calamities caused by a bark beetle (IpsTypographus (L.) belong to a long-term issue of spruce monocultures which are situated on non-natural places. These became current issues in the Tatra National Park in recent years. Submitted Diploma Thesis introduces an overview of current informations about the most significant factors allowing to spread of subcortical insects in mountain forests. It also deals with the topic of temperature significance in the evolution phases process on the example of bark beetle and the population development estimation using phenological models under climate changes conditions. In 2017 we observed and subsequently evaluated the meteorological data and a bark temperature in terms of the phenological development and the bark beetle generations count in the protected area of Vyšné Hágy. We also submit a model and the actually measured bark temperature comparsion in the thesis. We evaluated a capture in pheromone trap and compared a model and the actual swarming period in the protected area Vyšné Hágy.