Mosquitoes bite people in almost every country around the world. But is there a country that doesn’t have this bloody pest?
The answer is yes, there is one country without mosquitoes: Iceland. Neighbors, including Norway, Scotland and Greenland, are home to multiple mosquito species, but Iceland remains mosquito-free. (It’s worth noting that there are no mosquitoes either in Antarctica, but the Southern Continent is not a country.)
So, how is it possible for Iceland to not keep mosquitoes?
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Scientists have several theories. One idea is that mosquitoes have not yet reached Iceland. The island nation is separated from its neighbors by hundreds of miles of ocean, creating natural barriers and making it difficult for mosquitoes to arrive during flight.
However, mosquitoes are transported by plane. Gísli Már Gíslason, professor emeritus of Limnology (Lakes and Freshwater Studies) at the University of Iceland, confirmed this after catching mosquitoes on a flight from Greenland to Iceland. Moreover, mosquitoes can survive hours on aircraft landing gear, even at freeze temperatures, he said in a 2017 interview with Leikavik Grapevine, an English publication in Iceland.
So, if mosquitoes arrived, why didn’t they establish a population?
Related: Should we kill all the mosquitoes on Earth?
Zithrason explained that lack of proper breeding habitat is unlikely. Iceland has many ponds and marsh areas near the airport. It is the ideal place for mosquitoes to lay eggs. Instead, the most likely explanation is Iceland’s harsh climate.
The life cycle of a mosquito consists of four stages: eggs, larvae, pups (like caterpillar chrysalis) and adult. Adult mosquitoes put eggs in water. These eggs hatch to larvae, which occurs in pups. After that, adult mosquitoes appear from the pup.
Robert Jones, an insect biologist and assistant professor at the London School of Hygiene, told Live Science that mosquito larvae need unfrozen liquid water to develop. In very cold regions like the Arctic Circle in Canada, dormant during the egg season will survive mosquito species, where they can withstand months of frozen water.
“In warmer regions, such as parts of Central Europe, mosquitoes survive the winter as eggs or larvae in relatively protected waters that do not freeze, or as adults hidden in dens or other protected areas,” he said.
Icelandic climate lies between autumn and spring winter winter and the frequent freeze-thaw cycle. “These cycles disrupt development and allow mosquito eggs and larvae to emerge as adults, making populations much more difficult to establish,” Jones said.
Icelandic geothermal pools are not registered in winter, but temperatures may be too warm for larvae of mosquito species that are adapted to high latitudes. “Additionally, the chemical composition of geothermal water is unlikely to be suitable for mosquito development,” he said.
However, due to climate change, Iceland’s mosquito-free state may not last forever. Jones noted that warm springs and autumn could produce more unprocessed, existing water for a longer period, allowing mosquitoes to establish permanent populations.
Imo Hansen, professor of biology at New Mexico State University, agrees. “We are currently seeing tropical mosquitoes expanding the north region of the United States,” he told Live Science.
If mosquitoes had finally spread to Iceland, it would not be the first time that a mosquito-free zone has disappeared. Hawaii, the world’s most isolated archipelago, was mosquitoless until 1826, when European and American ships misrepresented it. Thanks to Hawaii’s positive climate, mosquitoes flourished and spread rapidly throughout the island. Since then, climate change has pushed mosquitoes into Hawaii’s de-elimination forests, which has once been too cool for them to survive.
Despite the possibility that mosquitoes will arrive in Iceland, the risks of disease-carrying species – species such as species known to transmit diseases such as dengue and chikungunya remain low for these insects to survive as they require tropical and subtropical climates, Jones said. Southern Europe faces increased risks of such outbreaks due to climate change and modern transport, but modeling research suggests that by 2080 Northern Europe will remain largely inappropriate for dengue infections,” he said.
Antarctica Quiz: Test your knowledge of the frozen continents of the Earth
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