Engorged females of Aedes albopictus, Ochlerotatus scapularis, Culex nigripalpus and Culex quinquefasciatus were collected by aspiration and sweep net during two years in Tremembé county, State of Säo Paulo, Brazil. Of the 1,092 specimens analyzed with the precipitin test, 87.6% reacted to one or more of the eight antisera tested. Of the four species for which the host determination was made, the reaction in 98.5% was to a single host. The application of the feeding index for four species of mosquitoes in Tremembe represented an attempt to measure and compare mosquito feeding patterns on these domestic hosts to evaluate the potential risk the region presents for the introduction and dissemination of arthropod-borne diseases. The results of the feeding index showed that Ae. albopictus commonly fed on humans and cattle; Oc. scapularis fed more upon cattleand dogs; Cx. nigripalpus fed on a wide range of hosts, and Cx. quinquefasciatus presented similar behavior but humans and dogs were the most common. The analysis of the feeding index agrees with the reported host feeding patterns of the four species investigated.