Female overwintering Culex pipiens complex mosquitoes were collected in February and March, 1979, in Memphis, Tennessee. Following shipment to Fort Collins, Colorado, and acclimation to laboratory conditions, the DV/D ratio of male progeny of these mosquitoes were determined. Based on the interpretation of DV/D rations, approximately 50% were intermediate forms, 40% P. pipiens, and 10% P. quinquefasciatus. The data indicate that in the Memphis area, a small proportion of the overwintering population will be quinquefasciatus-like, even though quinquefasciatus has been shown to hibernate.