Common mosquito, Asian tiger mosquito: Germany faces mosquito plague

The current mix of heat and humidity in Germany provides ideal breeding conditions for mosquitoes, especially the common house mosquito and the invasive Asian tiger mosquito. "Humid, warm weather means ideal conditions; mosquitoes are in their element," warns mosquito expert Doreen Werner from the Leibniz Centre for Agricultural Landscape Research (ZALF). While the native house mosquito mainly uses standing water such as rain barrels or puddles to lay its eggs, the invasive Asian tiger mosquito is far more adaptable: even the smallest amounts of water left in plant pot saucers or watering cans are enough for it as a breeding site. This allows it to spread rapidly even in densely populated urban areas. The biologist points out that the current humid and warm weather pattern allows several mosquito generations to develop over the course of a single summer. By the end of August the population is at its peak – which is reflected in the much more frequent bites at that time. By contrast, extreme dryness can limit mosquito populations because suitable breeding waters are then lacking. Researchers are currently taking a very close look at the Asian tiger mosquito in particular, as it originates in the tropics and is becoming increasingly established in Europe. It is not only active during the day and highly aggressive, but can in principle also transmit pathogens such as dengue or chikungunya viruses – although there have so far been no locally acquired chains of transmission in Germany. Chikungunya fever is rarely fatal, but can cause long-lasting health problems. Typical symptoms include high fever, severe joint pain, muscle and headaches, and skin rash. Dengue fever typically presents with high fever, severe headache and limb pain, and skin rash. In severe cases the disease can lead to bleeding and life-threatening complications. According to NTV, the Asian tiger mosquito has so far been found mainly in south-west Germany. Experts expect it to spread further north in future and become permanently established there as well. This is what the Asian tiger mosquito looks like The Asian tiger mosquito reaches a size of only up to 0.9 centimetres and is therefore relatively small. It differs from native mosquitoes above all through its distinctive black-and-white markings. According to the German Environment Agency, its abdomen and hind legs in particular are strikingly patterned in black and white. Another characteristic feature is a white stripe that starts at the back of the head and runs to the base of the wings. In many municipalities, sightings of the tiger mosquito can be reported via official online portals. In cities such as Freiburg im Breisgau, sightings of the Asian tiger mosquito can be reported via the city’s or the public health authority’s website. Heidelberg also has an online reporting form for tiger mosquito finds as part of local control measures. In Karlsruhe and the Middle Upper Rhine region, public participation in tiger mosquito monitoring is likewise well established, with reports often submitted via municipal health or environmental authorities. In Mannheim, residents can usually report such finds via the public health authority or environmental portals as well. Native mosquitoes also spread West Nile virus The West Nile virus, which is transmitted to humans by native mosquitoes, is now circulating in parts of Germany. According to a study by the Charité hospital, it has already become permanently established in Berlin. According to the Robert Koch Institute, a total of 14 West Nile cases were recorded across Germany in 2025. In 2024 there were 49, and 16 cases were reported in 2023 – in each case including infected travellers returning from abroad. Experts assume the actual number of cases to be significantly higher, as many infections cause no symptoms. When symptoms do occur, they are usually flu-like, with headache and limb pain, chills or vomiting. In rare cases an infection can take a severe course and prove fatal. Heartworm disease in animals Both the common mosquito and the invasive Asian tiger mosquito can also act as so-called vectors, meaning they can ingest the larvae of roundworms and pass them on. Dirofilaria immitis and Dirofilaria repens are parasitic roundworms that primarily infect animals, but can in rare cases also infect humans. Dirofilaria immitis causes what is known as heartworm disease, in which the parasites settle in the heart and pulmonary arteries and can cause severe heart and lung damage, especially in dogs. Dirofilaria repens, by contrast, affects the subcutaneous tissue and there usually leads to nodular or migrating swellings, including in humans as accidental hosts. Incidentally, coconut oil is often cited as a natural mosquito repellent because it contains lauric acid, which can have a deterrent effect on mosquitoes. Whether it could also help against the Asian tiger mosquito is not yet known. Experts generally recommend repellents with proven active ingredients.