A survey of mosquitoes which are attracted to and readily feed upon lizards in a northcentral Florida area where there is a relatively high prevalence of Plasmodium floridense in Anolis carolinensis was conducted. Culex erraticus and Cx. territans, collected in lizard-baited traps, readily fed on lizards in the traps and in the laboratory, and the former mosquito species is an experimental vector of Plasmodium floridense. Sporozoites were observed in the salivary glands from 11 to 14 days at 21-25 degrees C following an infective blood meal. The prepatent period of P. floridense in A. carolinensis at 18-24 degrees C was relatively long, 24-25 days (n = 2). At 32 degrees C, the prepatent period was decreased to 13-17 days (n = 4). The transmission rate of P. floridense by bite of Cx. erraticus and intraperitoneal inoculation of sporozoites from the salivary glands of Cx. erraticus, was relatively low (16.2%). Peak parasitemias ranged from 912 to 4,280 parasites per 10,000 red blood cells. Sporogonic development of P. floridense in Cx. territans which fed on infected lizards was not observed.