Summer's coolness rather than winter's cold limits the number of butterflies in the Arctic and subarctic. Fahrenheit above the ambient temperature. In the North, some species of butterflies tend to be darker than their southern relatives so they can absorb more heat. Also, northern butterflies tend to be smaller in response to the stress of a cold environment. This is an interesting contrast to northern mammals, which are bigger than their southern relatives.
Mammals generate their own heat, so there is an advantage to being large.
In winter butterflies are inactive. Some species overwinter in the adult stage and avoid freezing damage to their body by making a sort of antifreeze in the fall. Other species will overwinter in the larval stage. Butterflies are insects in the order of Lepidoptera. Most have two pairs of wings.