We evaluated the mating ability of male western corn rootworms, Diabrotica virgifera virgifera Leconte (Coleoptera: Chrysomelidae), for 20 d after initial mating, using a series of laboratory experiments. Males mated an average of 2.24 times within 10 d after their first mating and averaged 0.15 matings between days 11 and 20 after their first mating. Because estimating the mating frequency in Bt/ refuge cornfields is critical to developing robust and reliable models predicting Bt resistance development in this pest, we discuss how these laboratory findings may influence development and evaluation of current and future insect resistance management plans.