The 1st Aedes albopictus specimen recorded from Colorado was found near a tire storage site in Ft. Lupton on July 9, 2003. Intensified surveillance at the site in 2003 did not result in collection of any other specimens that season, leading to speculation that it was an isolated incident rather than an actual introduction for the species. Control measures against larvae and adult mosquitoes were conducted in the area to further reduce the likelihood of establishment of a viable population. However, subsequent surveillance during the 2004 mosquito season resulted in collection of 21 additional specimens at and near the Ft. Lupton site, possibly representing an established viable population of the species.