The importance of seasonal variation in hair coloration for thermoregulation of Ctenucha virginica larvae (Lepidoptera: Arctiidae)

ABSTRACT. . A marked seasonal variation in the hair colour of Ctenucha virginica (Esp.) larvae is observed under field conditions. During the autumn and spring larvae are black and yellow, while during the summer they are predominantly yellow. Under sunny conditions in the field, or when exposed to a radiation heat source in the laboratory, black and yellow larvae have significantly higher body temperatures than yellow ones. As larvae feed over a limited range of temperatures, it is proposed that seasonal changes in hair colour may help larvae to thermoregulate, thereby maintaining body temperatures within the range where feeding is possible.