Disease-induced lethargy can diminish host capacity to repel or kill biting mosquitoes. We exposed house finches (Carpodacus mexicanus) to mosquitoes (Culex pipiens pipiens), repeated the experiment after inoculating finches with Mycoplasma gallisepticum, and then repeated the experiment with the same birds after curing their infections. We videotaped avian behaviors before and during mosquito exposure, identifying hosts through blood meal DNA fingerprinting. Results revealed heterogeneity in mosquito preference regardless of infection. Mosquitoes choosing between two healthy finches were more likely to feed upon the same individual bird consistently. When one bird was sick, mosquitoes exhibited no preference. Sick birds made fewer total defensive behaviors than healthy birds, but only foot stomps were associated with reduced mosquito feeding success. Our results suggest that Mycoplasma and other avian infections that alter bird defensive behavior may influence mosquito feeding patterns and transmission of arthropod-borne pathogens such as West Nile virus.