Movement of Ochlerotatus japonicus japonicus into virus-endemic areas in the USA has raised concern about its vector potential and prompted monitoring of its spread. The abundance and seasonal distribution of Oc. japonicus in southwestern Virginia was measured in 2003 and 2004 using gravid traps. In 2003, collections were made over 192 trap-nights from June to August yielding 5,879 mosquitoes of which only 24 were Oc. japonicus. In 2004, 12,151 mosquitoes were trapped from June to September over 160 trap-nights. Ochlerotatus japonicus was the second most abundant mosquito species and the dominant Ochlerotatus species collected in gravid traps. Ochlerotatus japonicus was collected in low numbers in June, but the abundance increased significantly in July and remained consistent throughout the rest of the season. Of the other major mosquito species collected in this study, only Aedes albopictus exhibited a similar seasonal pattern as Oc. japonicus. Other biological similarities of Oc. japonicus and Ae. albopictus are discussed.