Might Asian tiger mosquitoes venture south from Zurich to Zug?

The city of Zurich recently announced that a population of Asian tiger mosquitoes (Aedes albopictus) had been found to have spent the winter in Wollishofen in the canton, this after they had also been found in Basel in 2015 and on a car park in the city of Zurich in 2016.

Fortunately, there have been no signs of the mosquito in Zug so far, though the canton, along with others, has been preparing for some time for just such an eventuality, as Florian Weber, the cantonal director of planning, confirmed, “preparing” in this context meaning how to get rid of the insects, and testing attempted eradication on a related fly, the Aedes japonicus.

As Gabi Müller of the Pest Control and Advisory Centre in Zurich explained, this latter-mentioned fly is already widespread across central plateau area of Switzerland and needs the same type of conditions as the tiger mosquito. However, unlike the Asian tiger mosquito, it does not bring with it the risk of disease.

As to how to avoid the spreading of mosquitoes in general, the advice was given to make sure rain collection troughs were kept tightly closed, as mosquitoes often make use of the slightest crack to gain access and breed by the stagnant water. Similarly, it was advised not to leave water standing in watering cans and suchlike, as it is in such containers that the mosquitoes lay their eggs, which go on hatch when the water level rises, each egg taking about a week to develop into a fully-fledged mosquito. Fortunately, if there are fish in the water near where the mosquitos lay their eggs, the latter are eaten.

Locals are therefore asked not to leave standing water where mosquitos could gain access to it and the authorities would also like to hear from members of the public who come across the mosquitoes, which are easily identified by the black-and-white markings on their legs and, in the case of the tiger mosquito, the white line on its back (photograph), compared with the generally yellowy-brown markings of indigenous flies. It was pointed out, too, how the tiger mosquitos bite in the daytime, the resulting effect noticeably more painful, too.

If you see one, the authorities would like you to catch it and freeze it in an undamaged state, for example at temperatures of -18°C for at least an hour, or longer in the freezing compartment of a fridge, and then place it gently on cotton wool prior to sending it off in an appropriate container (not loose) to Müller at number 31 Walchestrasse, 8006 Zurich, or in the case of one found in Zug, to the Office of the Environment at number 5 Aabachstrasse, 6301 Zug. The authorities of the municipality where the mosquito was found will then take appropriate action.