Phenological Study of the Spruce Bark Beetles Ips typographus (L.) and Pityogenes chalcographus (L.) (Coleoptera: Curculionidae) on Tara Mountain, Serbia 2025 South-East European Forestry SEEFOR volume: 16 number: 2 Abstract This study presents a detailed phenological analysis of two important spruce bark beetle species, Ips typographus (L.) and Pityogenes chalcographus (L.) (Coleoptera: Curculionidae), in the region of Tara Mountain in western Serbia, conducted over a period of three years (2016–2018). Field observations were complemented by growth degree days (GDD) calculations to determine thermal thresholds for development under local climatic conditions. Both species were found to be univoltine, with the potential for a sister generation. Timing of life stages, particularly adult emergence, was closely linked to accumulated thermal units, with developmental thresholds of 557 GDD reached between early and mid-July each year. The results highlight the influence of microclimate and temperature variability on bark beetle development and illustrate the potential for phenological shifts under future climate scenarios. These findings provide a regional framework for predicting outbreaks and improving forest pest control strategies in the face of ongoing climate change. https://unilib.phaidrabg.rs/o:8488 doi:10.15177/seefor.25-16 http://creativecommons.org/licenses/by/4.0/legalcode eng application/pdf 3395378 bytes Milosavljević, Marija Tabaković-Tošić, Mara Stajić, Snežana Češljar, Goran Mitrović, Suzana info:eu-repo/semantics/article voltinism; European spruce bark beetles; growing degree days (GDD); climate change; western Serbia