On 6 May 2018 an adult male mosquito was hand collected by the Commonwealth Department of Agriculture and Water Resources during a routine inspection of a vessel arriving at Darwin’s Stokes Hill Wharf from Papua New Guinea. Following the inspection, the vessel was granted coastal status, and subsequently moved to Fisherman’s Wharf to unload cargo and the Duck Ponds to await further domestic deployment. The mosquito was tentatively identified as the dengue mosquito, Aedes aegypti. The vessel having visited domestic wharf areas in Darwin, without the actual Ae. aegypti breeding site located, triggered precautionary mosquito surveillance and control measures at all three wharf areas, and a subsequent vessel inspection, during which an alive female Ae. aegypti was collected on deck of the vessel. The situation was up-scaled to ‘high risk’, with the response escalated to a comprehensive detection response as per the Commonwealth Department of Health’s ‘Response Guide for Exotic Mosquito Detections at Australian First Points of Entry’. During insecticide treatment of the vessel, the cryptic mosquito breeding site was located and eliminated. No further exotic mosquitoes were detected during the six week enhanced surveillance period.