The Colorado potato beetle is a major worldwide pest of potato and several other solanaceous plants. Insecticidal resistance is a serious problem in the northeastern and mid-Atlantic regions of the United States and a developing problem in other potato production areas of the United States and Canada (Forgash 1985; Johnson and Sandvol 1986; Boiteau et al. 1987). In the northwestern United States, insecticides applied to control the green peach aphid also control Colorado potato beetle, but these insecticides are likely to become ineffective due to the development of resistance or unavailable because of restricted use and environmental concerns. Biologically based management strategies are needed to reduce dependency on insecticides; these strategies require new basic knowledge including understanding prolonged diapause in populations of the Colorado potato beetle. Krysan et al. (1986) established that the occurrence of prolonged or repeated diapause can influence management strategies for insects, especially with respect to crop rotation.