This huge tiger moth, with a wingspread of sometimes two and a half inches or more is a lover of the cold north, for it is found everywhere in northern Europe, Northern Asia, and northern America. It is subject to considerable size and color variation due to different climates in the northern lands. Some places it has a wings spread of only about two inches and the hind wings are pink with black spots instead of yellow, while the forewings have much darker brown markings than those shown in the picture. This second form would be more likely to live in the dark woods where such darker colors would give it better camouflage whereas the first and larger form would live in more open places where lighter form would live in more open places where lighter colors are helpful.
Like other tiger moths it loves to sit still under a bright electric light, apparently absorbing the heat. Then suddenly a frenzy seems to take hold of it and it dashes itself up and against the burning globe in an overwhelming urge to be nearer the source of light. Why many moths do this is not clearly understood beyond the fact that the bright light causes a nerve center inside their bodies to force them to approach the light even as you would rush toward a light if you had been lost in a dark forest for some hours and suddenly saw a distant lantern.