The gypsy moth is a polyphagous butterfly spread throughout the northern hemisphere. Gypsy moth has characteristic periodic outbreaks, and due to its polyphagous nature and capabilities for longitudinal and latitudinal expansion it is considered one of the significant biological agents causing disturbances and damage in forests of Europe. The damage is generally higher from west to east and from north to south. Complex of natural enemies play a strong role in the regulation of the gypsy moth population density and dynamics, but the genetic diversity on the other hand significantly contributes to the adaptive capacity and survival of the species. The outbreak occurence varies between different regions of Europe, which raises the question of possible genetic differences between populations, additionally supported by the known consequences of quaternary glaciations. Using the COI mitochondrial DNA marker, 497 specimens from 38 sites in Europe were analyzed. Generally high genetic diversity and significant structure of the 8 major phylogenetic groups was observed. Recolonisation pattern of gypsy moth is congruent with the butterfly paradigm, with Dinarid Alps acted as a barrier for the Illyrian genes. Populations from Georgia have significantly different haplotypes from the rest of Europe, but in the context of the predicted gypsy moth range shift as a result of climate change they dont represent a high risk. However, the Illyrian populations that possess the highest genetic diversity represent a high risk in the event of expansion in genetically poor populations in highly valuable forest stands of continental basin of the Balkan Peninsula