A survey of the genetic variation in the ability to produce brown pupae was conducted using 23 broods reared from wild caught females. In addition a selection experiment was designed to investigate the genetic basis of the dimorphism. It was concluded that the genetic basis of the dimorphism is a threshold trait with quantitative genetic variation underlying the two phenotypes of green and brown pupal color. It was further concluded that the dimorphism is maintained in nature by weak stabilizing selection, thus explaining the occurrence of mismatches in pupal and background color. / Master of Science