The carniolan bee (Apis mellifera carnica) is a native race in the Republic of Croatia and inhabits several countries in Europe. The success of bee overwintering has significantly declined in the last decade due to various factors such as diseases, pests, climate and environmental factors, beekeeping techniques, and many others. The aim of this study is to calculate the overwintering index of honey bee colonies with regard to genetics; overwintering in colonies significantly depends on whether the examined colonies are in their original location or in an environmentally different location. The research was conducted from October 2022 to or in an environmentally different location. The research was conducted from October 2022 to April 2023 at the OPG Zlatko Elveđi in Gorica near Zadar. Two ecotypes of carniolan beesbees were used for the research. The aim was to monitor the overwintering of colonies comparing two ecotypes. Part of the colonies were treated with oxalic acid, other colonies were treated with amitraz (acaricide). Colonies of mediterranean ecotype colonies, had a lower population of bees with higher variability comparing to continental ecotype. Nevertheless, colonies treated with amitraz had a higher average strength but also greater variability, while colonies treated with oxalic acid showed a significantly higher number of bees. Colonies of mediterranean ecotype had 32% more bees in spring than in autumn 2022., with an increase in the number of bees in spring 2023 compared to autumn 2022, while colonies of continental ecotye had 20% more bees in the same period.