The box tree moth (Cydalima perspectalis Walk; Lepidoptera, Crambidae) origins from East Asia. It was probably brought to Europe in 2005–2007 along with boxwood bushes (Buxus spp.) imported from China. In Europe, it was recorded for the first time in 2007 in south-western Germany, Switzerland and the Netherlands. Without encountering any natural enemies, it quickly became an invasive alien species that threaten plants of the genus Buxus, both wild and cultured. There is a risk of its migration to other host plants. In Poland, C. perspectalis was found for the first time in 2012 in the south-western part of the country. From 2015, it was recorded in subsequent provinces of southern Poland, and a year later it appeared in the east (Outer Subcarpathia). The direction of its expansion eastwards suggests a natural way of expanding the acreage. In 2017 it was found in the central part of the country. In the 2018 growing season, boxwood plants were utterly destroyed for the first time in many Poland regions. In the following years, insects between Poland’s western and eastern borders occupied different areas to the north. By the end of 2020, C. perspectalis was found all over Poland. As it is not a quarantine pest in the European Union, it is not subject to official monitoring in Poland. Hence the lack of official information on the range of occurrence in the country. The studies conducted in 2018–2020 determined the current range of C. perspectalis occurrence in Poland, along with the selection of places with the highest intensity of occurrence. The caterpillars are most harmful in Poland’s southern and central part, where their foraging leads to total defoliation. The Polish climatic conditions allow the pest to develop without any obstacles two generations a year. In the warm year of 2019, the third generation was observed in large numbers. The insect poses a real threat to box trees in Poland, including the historic boxwood garden arrangements.