Geneva authorities say the tiger mosquito begins reappearing with warmer spring temperatures.
Officials say this is the critical period to prevent breeding before summer.
The invasive species lays its eggs in small amounts of standing water, such as plant saucers or watering cans, which should be emptied regularly.
The tiger mosquito can carry diseases including dengue fever, prompting local authorities to stress prevention at household level.
While municipalities treat public areas, officials say private gardens remain a key source of spread.
Residents are being urged to act collectively, as even small pockets of stagnant water can allow the mosquito to establish itself across neighbourhoods.
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