This study investigated the physiologically adaptive significance of elytral coloring and other thermal adaptations to different climes of Central and Northern Europe in a leaf beetle. Adults of Chrysomela lapponica L. differ in the coloring pattern of their red and black elytra when comparing populations from Finnish Lapland (Northern Europe) and from the Czech Republic (Central Europe). While the elytra of adults of the Czech population were bright red in color with a proportion of 51% of black marks, the relative size of the black marks of the Finnish beetle’s elytra was significantly higher (68%). When exposed to light, the dark morphs from Finland increased their body temperature within a shorter time and reached higher mean body temperatures than the lighter morphs from the Czech Republic. The walking speeds of the two different morphs did not differ at temperatures of 20, 15, and 10°C. However, at 5°C, the walking speed of the melanic beetles from Finland was significantly higher. The specific metabolic rate during overwintering of the adults was significantly higher in the Finnish morph at a temperature of 5°C compared with the Czech morph. The average and maximum temperatures during overwintering in the leaf litter layer in the Czech Republic were more variable and on average higher than under the snow cover in Finland. These results on the thermoregulation in C. lapponica are discussed with special respect to melanic elytral coloring as adaptation toward lower ambient temperatures.