In North Carolina, Precis coenia that emerge during the Summer months exhibit a ventral hindwing (VHW) with well-defined reddish-brown and brown pattern elements on a light tan background. During late Summer and early Fall, however, individuals begin to appear with poorly defined or obscured pattern elements on a dark reddish-brown background. The present study shows that the Fall (rosa) color morph can be induced by either low rearing temperatures or short daylengths. The effect of such conditions seems to be cumulative throughout the larval life, although animals are much more sensitive during the last 24 hours of larval life and immediately after pupation.