The study investigates the latitudinal patterns of insect thermal tolerances, focusing on upper and lower lethal temperature limits. The results show that upper thermal limits exhibit little geographical variation, while lower bounds of supercooling points and lower lethal temperatures decline with latitude. However, the upper bounds do not show a similar trend, leading to increased variation in lower lethal limits with latitude. These findings provide some support for the physiological tolerance assumption underlying Rapoport's rule, which posits that species can attain wider latitudinal extents due to greater climatic variability. The study also highlights the need for coupled data on species tolerances and range size to fully understand the climatic variability hypothesis.The study investigates the latitudinal patterns of insect thermal tolerances, focusing on upper and lower lethal temperature limits. The results show that upper thermal limits exhibit little geographical variation, while lower bounds of supercooling points and lower lethal temperatures decline with latitude. However, the upper bounds do not show a similar trend, leading to increased variation in lower lethal limits with latitude. These findings provide some support for the physiological tolerance assumption underlying Rapoport's rule, which posits that species can attain wider latitudinal extents due to greater climatic variability. The study also highlights the need for coupled data on species tolerances and range size to fully understand the climatic variability hypothesis.