Tips from the city health department: tiger mosquitoes love urban climates

The Asian tiger mosquito (Aedes albopictus) originally comes from Southeast Asia. It has been spread around the world for decades as a result of globalized trade and travel. It was first discovered in Europe (Albania) in 1979. Around 10 years later, the Asian tiger mosquito appeared in Italy (Genoa), presumably introduced from North America, and has since spread northwards across the Mediterranean region. In 2007, it was first detected in Germany at a highway parking lot on the A5 near the German-Swiss border. Since then, the Asian tiger mosquito has been found in Thuringia, North Rhine-Westphalia, Rhineland-Palatinate, Baden-Württemberg, Bavaria and Hesse. In summer 2018, it was detected in a residential area of the city of Frankfurt am Main.

The Asian tiger mosquito measures approx. 0.5 - 1 cm and is a relatively small mosquito compared to our native species. It has striking black and white stripes all over its body. This clearly distinguishes it from other native mosquito species. It is usually confused with the ringed snake (Culiseta annulata), which is larger and has black-yellow or black-brownish stripes. In contrast to the ringed snake, the Asian tiger mosquito is also diurnal. A particularly striking feature of the tiger mosquito is the white stripe that extends from the back of the head across the back to the base of the wings.

The tiger mosquito is a very adaptable species of mosquito and is able to produce dry and cold-resistant eggs. While the larvae and pupae of the mosquitoes die at temperatures below 11 °C, the eggs of the adults can survive temperatures as low as -10 °C. It is therefore possible that a new generation of mosquitoes will hatch from the eggs in spring, even if the larvae, pupae and adults do not survive the winter. The advancing climate change and the resulting milder winters also contribute to the tiger mosquito feeling at home in our latitudes.

As with other mosquitoes, only the females suck blood, which they need to produce their eggs. The tiger mosquito is active during the day and is very keen to bite. The bite of the tiger mosquito itself is rather harmless and is usually accompanied by the typical unpleasant consequences of a mosquito bite such as itching and swelling of the affected area.

However, the Asian tiger mosquito is a potential carrier of various pathogens. It is capable of transmitting dengue, chikungunya, West Nile, Zika and yellow fever viruses. However, the mosquito does not naturally carry the pathogen. The tiger mosquito must first bite an infected person who has such viruses in their blood in order to become a carrier itself. The tiger mosquito has the ability to feed on several individuals in quick succession, which increases the transmission potential. In Hesse, none of these infections caused by a tiger mosquito have been documented to date.

The most effective and sustainable protection is to prevent mosquitoes from breeding and thus prevent them from settling in the first place. The colonization of tiger mosquitoes on your own property or in your own garden can be prevented in simple ways by avoiding unkempt accumulations of water on the property and in the garden over the summer as far as possible.

Accumulations of water in flowerpot saucers, unused watering cans or buckets should be avoided and rain barrels should be covered. Water in bird baths or paddling pools should be replaced at least once a week. In addition, rain gutters should be cleared of leaves several times a year to prevent water from accumulating in them. When tending graves in the cemetery, you can make sure that unused flower vases are turned upside down.

Ponds also provide a breeding ground for mosquitoes. Fish and the insects that live in natural garden ponds, such as dragonfly larvae, water beetles and water bugs, eat mosquito larvae and thus naturally reduce the number of mosquitoes. However, these natural antagonists are lacking in newly created or non-natural ponds. You should therefore promote the biodiversity of your garden pond. If the unwanted mosquitoes have actually settled, biological control agents such as B.t.i. tablets can be used following expert advice. As with all mosquitoes, conventional means such as mosquito sprays and mosquito nets help to keep the animals away. Otherwise, long, waterproof or impregnated clothing protects you from bites.

According to the current state of the spread of the pathogens transmitted by the Asian tiger mosquito, a mosquito bite in Germany or Hesse is no cause for concern. You can treat the bite like a normal mosquito bite, for example with itch-relieving ointments. If you suddenly experience flu-like symptoms such as fever, chills, severe headaches or exhaustion a few days after a bite, you should consult a doctor to clarify the cause. The same applies in particular if the symptoms occur after a stay abroad in risk areas where both mosquitoes and pathogens are common, for example after a vacation in southern European countries, Southeast Asia or Central and South America.

If you have any health questions about diseases transmitted by the Asian tiger mosquito and other vectors such as Zika, dengue, yellow fever or chikungunya, your family doctor or the relevant health authority will be able to advise you. The family doctor will also provide information on possible vaccinations that should be carried out before a stay abroad in risk areas, including yellow fever vaccination before traveling to South America, for example.

Experts from the health and environmental sectors are keeping an eye on the situation in Hesse - so that the responsible authorities can react appropriately to possible new findings of the Asian tiger mosquito. The public is an important target group in the joint fight against the Asian tiger mosquito, as they can prevent the tiger mosquito from settling in their own gardens and properties by taking simple measures. Therefore, measures to inform the public - such as this FAQ - about non-native mosquitoes are extremely important. You can find out how to make your own property and garden mosquito-proof in our recommendations for action, among other things.

Captured mosquitoes can be sent for species identification to the so-called Mosquito Atlas, a Citizien Science project of the Leibniz Center for Agricultural Landscape Research (ZALF) e.V. and the Friedrich Loeffler Institute (Federal Research Institute for Animal Health). Become a mosquito hunter and contribute to the creation of the Mosquito Atlas of Germany. You will be making a valuable contribution to research and health protection. Further information on the project and instructions on how to send in your mosquitoes can be found at https://mueckenatlas.com/ (opens in a new tab)

The Asian tiger mosquito is very well adapted to the urban habitat. It prefers to use small standing and artificial pools of water such as flowerpot saucers, vases, rain barrels, blocked gutters or old car tires as breeding grounds. Such accumulations of water can be found on many properties and in people's gardens in spring and summer, which is why the tiger mosquito can spread wonderfully in residential areas. As you have the best view of the situation on your own property or in your garden, your help is needed. With just a few simple steps, you can take important measures to prevent the tiger mosquito from settling on your property. You can also catch mosquitoes and send them to the mosquito atlas for species identification.