Large cage and field studies were conducted to compare the efficacy of 2 American Biophysics Corporation mosquito traps, the standard professional (PRO) trap and a new counterflow geometry (CFG) trap. The PRO trap utilizes conventional downdraft technology and the CFG trap uses a patent-pending technology. In large cage studies, similarly baited CFG traps captured approximately 1.7 times as many laboratory-reared Aedes taeniorhynchus as the PRO trap. The CFG trap baited with CO2 + octenol resulted in significantly reduced landing counts compared to all other treatments; mean landing count was reduced from 233.8 (12.99/min), when no trap was present, to 24.7 (1.37/min). In field studies against natural populations of woodland species, the CFG trap captured 7.8 times more mosquitoes than the PRO trap overall, and approximately 11 times more Anopheles crucians, Anopheles quadrimaculatus, and Culex erraticus.