Three mosquitoes found in Iceland overturn a historic reputation

Three mosquitoes caught in a moth trap were enough to overturn Iceland’s long-held reputation. In October 2025, scientists confirmed the first wild specimens ever recorded in the country, which had until then been known as one of the few places on Earth without these insects.

How were mosquitoes found in Iceland?

The finding began on 16 October 2025, when Björn Hjaltason was inspecting a red-wine-soaked rope at the Kiðafell farm in the Kjós area. The bait had been set out to attract moths, yet it caught a female mosquito that drew his notice.

Two further specimens were found at the same site over the following days: one male and another female. The insects were sent to the Icelandic Institute of Natural Sciences, where entomologist Matthías Alfreðsson identified them as Culiseta annulata.

Why had Iceland not had mosquitoes?

Severe cold was never the sole reason, as mosquitoes also survive in even colder areas such as Greenland. Iceland’s principal barrier was the instability of its winters, when thawing spells were followed by abrupt temperature drops that disrupted the development of eggs, larvae and pupae.

Biologist Gísli Már Gíslason had previously explained that these sudden shifts could prevent the insects from completing their life cycle. Temporary warmth would trigger their development, but a rapid return to cold conditions would kill the young forms before they could reach adulthood.

What makes Culiseta annulata resistant to cold?

Culiseta annulata occurs in several parts of Europe and can endure winter in sheltered locations. Rather than relying solely on water throughout the cold months, adult mosquitoes can take cover in cellars, barns, outbuildings and other structures.

• Adults can overwinter in buildings protected from extreme temperatures.
• The species tolerates cold conditions across different northern European regions.
• Iceland’s marshes, ponds and shallow waters could provide breeding sites.
• Cargo transport is regarded as a possible route by which it entered the country.

This adaptability increases the likelihood that the species could remain in Icelandic territory. However, identifying three specimens does not yet prove that a breeding population exists. Further sightings will be needed to establish whether they have become established or were an isolated occurrence.

Did global warming help bring mosquitoes to Iceland?

The insects were discovered after a spell of unusual warmth in Iceland. In May 2025, Egilsstaðir Airport recorded 26.6 degrees Celsius. Higher temperatures may extend the period available for breeding and improve the survival prospects of species arriving from other areas.

A 2022 study published in Communications Earth & Environment found that the Arctic warmed almost four times faster than the global average between 1979 and 2021. Even so, scientists do not yet say that the climate directly caused the arrival of these three mosquitoes.

Does the discovery pose a risk to the public?

The species can bite, but it is not regarded as a significant carrier of dengue, Zika or chikungunya. The confirmation is therefore viewed chiefly as an ecological milestone and a potential nuisance, rather than a public-health emergency for Iceland’s residents.

The Icelandic Institute of Natural Sciences has asked the public to photograph or collect any further specimens for analysis. The next records will be decisive in showing whether a centuries-old natural barrier has truly fallen, or whether the three visitors disappeared before creating a permanent population.