Thule Air Base in western Greenland had a previously uncharacterized mosquito pest problem. Swarms of bloodfeeding mosquitoes have been reported from June to late August, but the species were unknown. We conducted a base-wide mosquito vector survey from June to July 2012. One species of mosquito, Aedes impiger, was collected and >3,000 were processed for polymerase chain reaction–based virus surveillance. Active mosquito breeding sites were located throughout the base and surrounding valley. Two pools of mosquitoes from Thule Air Base tested positive for an Orthobunyavirus; however, DNA sequencing of the viral amplicons was not complete enough to fully identify the agent.