A mark-recapture project examined dispersal and flight distances of Culex mosquitoes from a wastewater treatment plant in Albany, NY, during 2007 and 2008. A self-marking device was constructed to mark egressing mosquitoes with fluorescent marking powder. Mosquitoes were recaptured using 30 CDC miniature light traps located within a 2.0 km radius of the marking site. A total of 13 and 10 marked Culex mosquitoes were recaptured in 2007 and 2008, respectively. Culex mosquitoes traveled a minimum of 0.16 km, a maximum of 1.98 km and, following correction for decreasing trap density with distance, had a mean distance traveled of 1.33 km. Characterizing the dispersal patterns of these mosquitoes is important for understanding the distribution of West Nile virus and other pathogens.