Non-native European hornet, Vespa crabro, is widely distributed in the United States east of the Mississippi River. Occurrences of V. crabro to the west of the Mississippi River are comparatively sparse. The majority of documented specimens from the “Trans-Mississippi” region of the U.S. are primarily from the Ozarks Physiographic Province in Arkansas, Missouri and eastern Oklahoma, with only sporadic reports of solitary specimens from Arizona, California, Kansas, Louisiana, and Wisconsin. This patchy geographic distribution in the southern and southwestern United States suggests that V. crabro may be restricted by the upper lethal thermal limit of the species (44°C), which can approach summertime temperatures in those regions.