The Asian tiger mosquito (Aedes albopictus) belongs to the family of mosquitoes (Culicidae) and is characterized by a contrasting black and white coloration of the abdomen and legs. With a size of 0.5 - 1 cm it is smaller than most native mosquitoes and are recognisable by the following characteristics:

1. All legs have white scales, which appear as rings.
2. The last segment of the hind legs are white.
3. A white line runs from between the eyes to the back.
4. The ends of the palps (olfactory receptors) are white.

The Asian tiger mosquito is often confused with other striped insects. Please check the above-mentioned characteristics closely and review the size ratios again. The tiger mosquito is very small! In the photo, you can see the size in relation to a coin (Swiss five-centime piece).

If you think you have seen an Asian tiger mosquito or possibly even been bitten by one at home or elsewhere, please take the following steps:

1. Catch the mosquito without squashing it, e.g. with a glass and paper.
2. Freeze the mosquito overnight in the freezer.
3. Check whether it could be a tiger mosquito based on the identifying characteristics listed above. If the characteristics do not match your mosquito, it is most likely not a tiger mosquito and can be discarded.
4. Take a picture. The better the quality, the greater the chance for a successful determination! Make sure that you place the mosquito on a white background, e.g., on a white paper. Place a ruler or a 5-cent coin next to it so that its size can easily be estimated. Make sure that the insect is well lit and in focus before taking the photo.
5. Submit your tiger mosquito find with photo to www.muecken-schweiz.ch and follow the instructions.
6. Keep the mosquito for possible queries.
7. If you cannot take a photo, put the mosquito in a small padded container (matchbox with cotton wool or similar) and send it to the following address, with your name and contact details, where the mosquito was found, and the date it was found:

In Switzerland, the Asian tiger mosquito was first detected in the canton of Ticino in 2003. Following further individual findings, a stable, locally reproducing population was discovered for the first time in the Chiasso area in 2007. In the following years, the tiger mosquito spread further within the canton and established itself on a large scale.

Even north of the Alps, individual specimens are repeatedly introduced from the south by vehicles traveling along the main traffic routes - especially along the A2 motorway, and smaller tiger mosquito populations have been repeatedly detected in the cities of Basel and Zurich. Since the Asian tiger mosquito is only adapted to cooler climates to a certain extent - and thus its distribution is correspondingly limited - it is assumed that its distribution will increase with climate change.

The tiger mosquito originally comes from Southeast Asia, where it broods as a forest dweller, especially in tree hollows. With the increased distribution of the tiger mosquito, caused by the replacement of forest areas by settlements, they have penetrated further into urban areas and adapted to those conditions. Small stagnant bodies of water are prevalent and diverse in urban areas offering the tiger mosquito ideal conditions to breed and reproduce.  In addition, humans are ideal hosts for females, which are dependent on blood for egg production. From there, the Asian tiger mosquito has spread worldwide through global trade and international travel. The eggs of the Asian tiger mosquito are very resistant to drought and can therefore be easily transported between continents, for example with scrap tyres. Regionally, the Asian tiger mosquito spreads mainly along main traffic routes, as mosquitoes often follow people into vehicles.

In 1979, the tiger mosquito was discovered for the first time in Europe (Albania). Most likely, it was introduced with deliveries of used tires containing eggs. However, it is assumed that the tiger mosquitoes in Europe are mainly derived from populations in Italy. At the beginning of the 1990s, Asian tiger mosquitoes were introduced from the USA, which were already well adapted to a rather moderate climate and from there spread along the transport routes throughout the Mediterranean region and to Switzerland.

There is no evidence that COVID-19 can be transmitted by mosquitoes. The new coronavirus is a respiratory virus that is primarily transmitted via droplets from infected people that are produced when they cough or sneeze, or by droplets of saliva or nasal fluid.

The Asian tiger mosquito has been shown to transmit numerous infectious diseases, in particular Chikungunya and Dengue fever, as well as Zika viral diseases. Theoretically, it would also be possible that these diseases could be transmitted in Switzerland, where the Asian tiger mosquito occurs. For example, it would be possible that if a person returned from an area where these viruses circulate and became infected with them there, could be bitten by an Asian tiger mosquito here and thus spread the virus locally. That such local transmission cannot be ruled out in Europe either is demonstrated by the numerous cases of disease transmission in Europe due to infected travellers returning home and locally resident Asian tiger mosquitoes. However, no such transmission has yet been documented in Switzerland.

The risk of transmission depends on many factors such as mosquito density, ambient temperature or human behaviour. In order to keep the risk of transmission as low as possible, authorities are making various efforts to limit the spread of the Asian tiger mosquito by means of preventive measures and, where necessary, to combat it in a targeted manner.

In contrast to most native mosquitoes, the Asian tiger mosquito is predominantly day-active and perceived as very aggressive. Wearing light-coloured, long, non-tight clothing is recommend. In addition, mosquito repellents can help to keep the pests away. It is important to distinguish between products that are applied to the skin and those for clothing. You can find more information on this in our information sheet "Mosquito repellents" available in German, French and Italian.

The Asian tiger mosquito likes to lay its eggs in small stagnant pools of water such as rain barrels, flowerpots and trays, flower vases, animal drinking basins, blocked drains, rain gutters, unused watering cans and similar vessels. It is, therefore, worth checking your garden or balcony regularly for such breeding sites and, if possible, removing them so that the mosquito cannot reproduce. Pay particular attention to the following points:

• Avoid standing water in flowerpot trays or exchange at least once a week
• Do not pour stale water into the gully, but tilt it directly onto the ground or pavement
• Empty watering cans, buckets etc., after use and store upside down
• Remove leaves from gutters
• Regularly clean all water containers such as drinking troughs
• Regularly renew water in paddling pools and remove from toys
• Seal rain barrels with mosquito nets
• Prevent water accumulation on tarpaulins etc.

In Switzerland, there are various programmes for monitoring the tiger mosquito, both at national and cantonal level. These programmes usually consist of monitoring, prevention and control measures. "Active" and "passive" monitoring are used to collect information on the spread of the tiger mosquito. In active monitoring, mosquito traps are set up and regularly checked at potential introduction sites (e.g., motorway service areas, goods transfer points or port facilities) and in possible, or already populated areas in settlements (e.g., cemeteries, leisure gardens). The capture of mosquitoes is supplemented by sampling of possible breeding sites (larvae sampling).

Since it is not possible to set traps everywhere in Switzerland, the programmes are dependent on the support of the population. Therefore, we encourage you to become a mosquito hunter yourself and report suspicious mosquitoes to us! Preventive measures, such as avoiding breeding sites and the selective use of parricides, are intended to stem the spread of the tiger mosquito. Here, too, we are dependent on your help to prevent the formation of breeding sites in your own environment and make the life of the tiger mosquito difficult!

The Swiss TPH team supports several cantons in monitoring and controlling the tiger mosquito. Trap locations are identified, monitoring networks installed and regular inspection visits carried out. The data are then processed at regular intervals and sent to the cantonal authorities so that measures can be taken as quickly as possible. Our team is constantly working to make the collection, combination and evaluation of data even more effective and to review the latest strategies for controlling alien mosquitoes and adapt them to Switzerland.