Blood-fed mosquitoes were collected principally from urban sites in Iowa. Aedes mosquitoes fed predominantly on mammals; rabbits were the primary host of Ae. trivittatus and Ae. vexans. Ae. trivittatus frequently fed on birds where birds were a predominant part of the local fauna. This finding strengthens the hypothesis that Ae. trivittatus is a secondary vector of WEE virus in Iowa. Culex mosquitoes fed predominantly on birds; Culex spp. (Cx. pipiens, Cx. restuans and Cx. salinarius) exhibited a midsummer increase in their feeding on mammals. This may increase their vector potential. Nine, 13 and 8 multiple blood meals were identified for Ae. vexans, Ae. trivittatus and Culex spp., respectively. The incidence of multiple feeding contributes to the vector status of these Iowa mosquitoes.