The blood meal sources of 5 species (Mansonia titillans, Aedes scapularis, Culex quinquefasciatus, Coquillettidia shannoni, and Anopheles peryassui) collected in Conceição do Macacu, in the southeastern Brazilian state of Rio de Janeiro, were examined with the precipitin test. Of the 1,128 mosquitoes collected, 907 (80.4%) reacted to some antisera. Although all 5 species were eclectic in their feeding habits, Ma. titillans and Ae. scapularis fed mostly on birds, while Cx. quinquefasciatus, Cq. shannoni, and An. peryassui fed mostly on bovines. Proportions of mosquitoes feeding on 1 source varied from 60.0% (Ae. scapularis) to 87.7% (Ma. titillans), while that of mosquitoes feeding on >1 source varied from 12.2% (Ma. titillans) to 34.4% (Ae. scapularis). Epidemiological implications of the feeding and their potential involvements in the transmission of arboviruses are commented upon.