Iceland has no mosquitoes.
Why it is true
Iceland is one of the few countries in the world where mosquitoes do not exist. The cold climate and sudden temperature changes between winter and summer prevent these insects from completing their life cycle.
Source: Entomology
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This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.