This study presents results for the dynamic of the populations of the pine processionary moth ( Thaumetopoea pityocampa ) during the period 2007-2017 and the impact of reducing factors in the Repub-lic of North Macedonia. The population density was determined by the number of larval nests both per tree and per hectare that varied during the research period. The number of individuals went up between 2007 and 2010, while during the following years it rapidly decreased. Since 2011, an overall prograding trend has been recorded in the several subsequent years. This could be explained by the huge number of individuals from the previous years that were in a diapause. The abundance of pest populations continued to grow in 2016 as no measures were taken. During the winter of 2016/2017, the impact of the extremely low temperatures on pest mortality was monitored in 2016-2017 generation. The density of the populations came to latency due to the very large number of dead larvae of second and third larval stages. We recorded a 100% mortality of larvae in plantations of Pinus nigra in the regions near Prilep, Sveti Nikole, Shtip, Kochani and Negotino Villages.