This study determined whether the addition of a CO₂ nozzle made specifically for the BG-Sentinel™ trap increased the efficacy of collecting host-seeking mosquitoes, particularly Aedes albopictus and Culex spp., which includes Cx. pipiens, Cx. restuans, and occasionally Cx. salinarius in Fairfax County, VA. Twenty BG-Sentinel traps were incorporated into the Fairfax County West Nile virus (WNV) surveillance program: 10 traps were randomly selected each week to have the nozzle attached, and the remaining 10 traps were without the nozzle. The BG-Sentinel traps collected 20 mosquito species with the nozzle and 19 mosquito species without the nozzle. The traps with the nozzle collected 46.58 (SE 3.236) mosquitoes per 24-h trap-period and the traps without the nozzle collected 46.73 (SE 2.942) mosquitoes per 24-h trap-period, and no significant difference (P > 0.05) was found. There was no significant difference (P > 0.05) in the collection of Aedes albopictus, Culex spp., Anopheles punctipennis, Ae. vexans, and Aedes triseriatus between the traps with or without the nozzle. Other mosquito species were collected in low numbers and statistical analysis was not performed. Both the traps with and without the nozzle collected WNV-infected Aedes albopictus and Culex spp.