Field studies were conducted to determine the responses of mosquitoes associated with irrigated riceland in Arkansas to 1-octen-3-ol (octenol), carbon dioxide (CO2) and combinations of both. Octenol was released at 4.1 (wick in) and 41.1 (wick out) mg/h and CO2 at 200, 500 and 1,000 ml/min. Octenol alone did not result in a significant (P greater than 0.05) increased response for any species relative to unbaited traps. An increase in CO2 release rate generally resulted in an increase in collection size. All octenol + CO2 combinations increased the collections of Coquillettidia perturbans, Culex salinarius and Psorophora columbiae relative to equivalent CO2 release rates alone. Mixed responses for these same treatment combinations were obtained for Anopheles crucians, An. quadrimaculatus and Cx. erraticus.