Based on air temperatures measured at the altitude transit 1200 - 1500 m n. m. in the High Tatras in 2020 is the determination of the course of ontogenetic development of the spruce lichen-eater using the phenological model PHENIPS and published data on the temperature requirements of individual developmental stages. Modeled swarming dates which in our case were released for the month of June and the number of generations is compared with the catches in pheromone traps. We compared the obtained results with the condition of forest stands. Aerial photographs were used to assess the time changes of spruce stands. The present work deals with the importance of temperature and solar radiation for the course of developmental stages of Ips typographus and the estimation of population development.