Do mosquitoes really get attracted by light and sweet blood?
Many people, who sit outside in short clothing during long summer evenings - it couldn't be more beautiful for mosquitoes. The abundant rain showers this year, according to experts, lead to an unusually large number of mosquitoes being present. Which myths persist about them and which tricks really work against them?
Claim: Mosquitoes prefer sweet blood.
Rating: False.
Facts: Mosquito expert and biologist Helge Kampen identifies two errors in this statement. There is no sweet blood, and mosquitoes do not orient themselves on blood but on smells. They react to specific scent combinations or "scent cocktails," as Kampen calls them. These cocktails, according to Kampen, consist of two components: on the one hand, the exhaled air, that is, carbon dioxide, and on the other hand, the scent given off through the skin.
According to words from the Friedrich-Loeffler-Institute (FLI), there are differences in the "attractiveness" of a person. "We have 52 mosquito species in Germany, some of which differ," says Kampen. It is quite possible that a person in a certain region is stung by many mosquitoes, while in another region they are stung less.
Claim: Who drinks alcohol attracts more mosquitoes.
Rating: True.
Facts: An insect scientist and mosquito expert, Doreen Werner, explains that alcohol causes our veins to expand and thus increases blood flow and sweat production. The sweat smell is then the attractant that mosquitoes react to.
Several study results confirm this, for example, from the American Mosquito Control Association. The association for mosquito control had several probands drink a beer, while others remained sober. The mosquitoes were then presented with an arm of a sober person and an arm of a person who had drunk beer. The result: More mosquitoes landed on those probands who had drunk beer earlier.
Claim: Mosquitoes are attracted to light.
Rating: Almost not at all.
Facts: Mosquito expert Kampen states that only a few mosquito species react to light. However, stimuli such as CO2 or scent substances from the skin have a stronger effect. In addition, mosquitoes can detect the temperatures of humans at shorter distances. The closer a mosquito comes, the easier it can find a human. Therefore, Kampen advises that people who want to avoid mosquitoes run through their homes in the dark "Mosquitoes come even when the light is out."
The German Environment Agency (UBA) writes on its website about mosquitoes, that UV lamps offered for sale in the outdoor area are banned. The reason for this is that "mosquitoes are hardly attracted to UV light." Instead, many endangered insect species, such as certain moths, are attracted and killed by it.
Claim: Certain scent substances keep mosquitoes away.
Rating: True.
Facts: However, not every repellent has the same effect on insects, according to Entomologist Werner. People give off different amounts of CO2 and other scents and are therefore differently attractive to mosquitoes. "One says I can smear myself with lavender oil, the next says I must eat garlic and the third needs a chemical weapon from the pharmacy", explains Werner. What works best for each individual can only be determined through trial and error.
However, repellents must be properly dosed to reliably work and be tolerable for the skin, explains Biologist Kampen. The advantage of anti-mosquito products is that the used substances are standardized and thus the effectiveness is likely to be given. These products, which are mainly applied to the skin, can keep mosquitoes away for several hours, explains Kampen. However, the effect eventually wears off.
Claim: Spit on mosquito bites to relieve itching.
Rating: Partly correct.
Facts: The itching is not relieved by the spit itself, but by the cooling effect, explains Allergologist Mathias Sulk. Spit is not a "cure-all," says the head of Allergology at the University Hospital Münster. With it, bacteria from the oral mucosa can come to the skin. In particular, with fresh mosquito bites, this is not good. Sulk therefore advises: "I would rather give it water. It evaporates and has the same cooling effect."
In addition, heat can also provide relief. Specially designed heat wands give off a temperature shock for a few seconds. "This heat generates a pain stimulus and this covers up the itch," explains Sulk. It is important to use medical heat wand products and not, for example, to heat a spoon on the stove and apply it to the bite. Then, burns can occur quickly, warns the doctor.
Whether cold or heat is better at relieving itching is mainly a subjective feeling and varies from person to person, as the allergologist says. There are no studies that have investigated this. But: "One knows that both works."
Claim: Mosquitoes in Germany are not as dangerous as in other countries.
Rating: True - but this is changing due to climate change.
Facts: Mosquitoes are generally considered the most dangerous animals in the world: Above all, through the spread of diseases such as malaria, dengue fever, and yellow fever, "mosquitoes kill more people than any other creature on earth," according to the US Health and Human Services Agency CDC.
In Germany, people do not yet have to worry too much, says Mosquito expert Kampen. "Transmitted mosquito-borne diseases are still quite rare in Germany." However, this could change with climate change - as both certain pathogens and mosquito species from warmer regions feel increasingly comfortable here.
The Asian Tiger Mosquito, for example, which has been occurring in Germany for several years, is a "good vector for many dangerous viruses" like dengue and Zika virus, explains the biologist. However, there is still no known case where one of these diseases was transmitted here by such a mosquito. In southern countries like Italy, such transmissions have already occurred.
Statement: West Nile Virus is widely spread among native mosquito populations in Germany, first detected in Germany in 2018. Most infections in humans are asymptomatic, according to the Robert Koch Institute (RKI), around 20% of infected individuals develop a fever-like, grippy illness, and about one in every hundred develop encephalitis or meningitis.
Fact: In Germany, six infections were reported in 2023. However, experts believe there are likely many undetected cases. The common mosquito species (Culex pipiens), which transmits the virus, is widespread in Europe. Eradicating this mosquito is not a viable solution to contain the spread of the West Nile Virus, which has primarily circulated in certain eastern German federal states.
Claim: After a harsh winter, there are fewer mosquitoes.
Assessment: False.
Facts: Native mosquito species are well-adapted to the German climate and can withstand cold winters. The German Wildlife Foundation states on its website that mosquitoes have different overwintering strategies. Mosquito eggs are rarely damaged by frost.
What can be problematic for mosquitoes is fluctuating winter weather, according to Kampen. Mosquitoes adjust their metabolism to temperature conditions. When temperatures rise, their metabolism is activated again. If temperatures rise and fall frequently, the mosquito's body reacts and consumes energy.
"New species, such as those that have settled here from the tropics, are not well-adapted to this," says the mosquito expert. A relatively cold winter harms these mosquitoes more.
Despite the misconception that sweet blood attracts mosquitoes, they actually respond to specific scent combinations or "scent cocktails" that include carbon dioxide and substances released through the skin. Also, certain scent substances can indeed keep mosquitoes away, but the effectiveness varies among individuals.
