The Weather Channel, along with other news sources, reports that Iceland, which heretofore was mosquito-free, now has mosquitoes. Come next summer, you may want some insect repellent, especially near lakes or other wetter places. https://weather.com/news/climate/news/2025-10-21-mosquitoes-found-in-iceland-for-first-time
That leaves Antarctica (and maybe also the Faroe Islands) as the last place on Earth without those nasty bloodsuckers!