Field studies were conducted to determine the responses of mosquitoes found in north central Florida bay and cypress swamps to carbon dioxide (CO2), light, butanone, and 1-octen-3-ol (octenol), alone and CO2 in combination with each of the others. The response of these mosquito species to 5 CO2 release rates (2, 20, 100, 200, and 2,000 ml/min) of CO2 was also determined. The use of CO2 resulted in a response in all the species studied; the pattern of response to increasing CO2 levels varied from species to species. In general, collection size increased as CO2 release rate increased; however, 5 species (Aedes dupreei, Anopheles perplexens, Culiseta melanura, Culex erraticus and Mansonia titillans) deviated from this pattern. Collection size of Ae. dupreei, Cs. melanura, and Cx. erraticus decreased at the 2,000 ml/min release rate. Collection size of An. perplexens and Ma. titillans remained constant at each CO2 level to which these species responded. In the CO2 and light studies, the general pattern for collection size was: CO2 + light > CO2 alone > light alone. The combination CO2 + octenol (2.2 mg/h) resulted in a synergistic response (i.e., greater than the combined response obtained by CO2 and octenol alone) for all species except Cs. melanura, Culex nigripalpus, and Culex restuans. Only 2 species (Aedes atlanticus and Aedes canadensis) responded to octenol in relatively large numbers (i.e., response to octenol alone > or = 5% of that obtained by using CO2 alone at the 200 ml/min release rate). Octenol at the release rate tested repelled Cs. melanura. The butanone + CO2 bait combination increased the responses compared to CO2 alone of Aedes infirmatus, Culex salinarius, Coquillettidia perturbans, and Psorophora ferox, but decreased the response of Cs. melanura.