Finnish summer mosquito season split in two – expert says south saw unusually few, Lapland normal

Southern and central Finland have seen unusually low mosquito numbers this summer, while northern Finland and especially western Lapland have experienced normal or even high levels, according to an expert at the University of Oulu.

Professor Marko Mutanen said the sharp regional divide stems from differing weather patterns over winter and summer. In the north, heavy snowfall increased ground moisture, creating ideal breeding conditions. In the south, prolonged dryness has kept mosquito populations low.

“In northern Finland there’s more moisture in the terrain and suitable habitats, so mosquito numbers have been higher,” Mutanen said. He noted particularly high mosquito activity around Kilpisjärvi in western Lapland, where he traveled about a week ago.

Recent heavy rains may yet bring late-season mosquitoes to the south and center, he added. “It’s quite possible that more mosquitoes will appear, possibly even a new wave. Even in a normal year, certain species remain active into August.”

Mosquito eggs can survive in dry ground for several years and hatch during unusually wet periods, Mutanen explained. After multiple dry years, a single wet year can trigger a surge in hatching.

Public reaction online has reflected the uneven season, with many in southern and eastern Finland commenting on the lack of mosquitoes, while northern residents report normal levels.