A new, convenient method was developed to supply CO2 for mosquito sampling by using yeast,which converts sugar into CO2 and ethyl alcohol. The system could, at average, generate 32.4 ml/min of CO2for at least 27 h. The total weight of the CO2 generated was estimated to be 94 g. The efficacy of yeast-generatedCO2 as attractant for mosquitoes was significant, and the following 6 mosquito species were collected usingyeast-generated CO2 traps from July to September 2003 in a residential area of southern and northern YokohamaCity, Japan: Aedes albopictus (Skuse), Armigeres subalbatus (Coquillett), Culex halifaxii Theobald, Cx. pipienspallens Coquillett, Ochlerotatus japonicus (Theobald), and Tripteroides bambusa (Yamada). Besides...