There are a ton of mosquito repellents on the market, including sprays, ultrasonics, and perfumes. Two experts reveal how they work. And do they really help?
Woman protecting child with mosquito spray while walking Photo: LarsxHeidrich/imago
2024 is a mosquito paradise, as the humid and mild climate provides ideal breeding conditions for mosquitoes. Female mosquitoes lay eggs in standing water, such as puddles, rain barrels, and unused watering holes. This year, rainwater has definitely filled the water.
It started a few weeks earlier than usual in April. If you believe the mid-term weather forecast, it will be warm and occasionally rainy until the end of September. Mosquitoes have been with us for longer and longer periods of time in recent years, and this year will be no different.
People who spend time near lakes or rivers, react violently to mosquito bites, or have trouble sleeping at night because of buzzing noises take precautions. People would lure mosquitoes with old, sweaty socks and hang them as far away from their beds as possible.
Today, there are ways to reduce odor. Proven home remedies compete with artificially produced active ingredients and modern technology. But how effective are they? And what effect do they have on our health and the environment?
spray
The best mosquito repellents are chemical, says the World Health Organization (WHO). Experts recommend using so-called repellents, especially if you are in an area where diseases like dengue fever can be transmitted by mosquitoes. These are active ingredients that mosquitoes detect through their sense of smell and deter them without killing them.
The substances called diethyltoluamide (DEET) and Icaridin are considered effective. DEET was developed by the US military to protect soldiers from mosquitoes and was used in the Vietnam War. DEET is now included in popular sprays such as “Anti Brumm” and is said to protect against mosquito bites for up to eight hours.
Icaridin has a slightly shorter duration of action, but is considered better tolerated. DEET should not be applied to sensitive areas or permanently, as it can irritate mucous membranes and eyes, warns Tristan Jorde, head of the environmental and product safety department at the Hamburg Consumer Center. Manufacturers strongly advise against spraying DEET on children. “For young children, you should switch to natural alternatives such as Icaridin or lemon eucalyptus sprays,” says ecologist and mosquito researcher Renke Lühken.
Also, when used in higher doses, the active ingredients are harmful to living organisms and small aquatic life, such as birds and larvae. That’s why chemical sprays should only be used when there is a real risk of mosquitoes, says consumer advocate Jorde.
Ultrasonic device
Ultrasonic insect repellents are often marketed as a gentle alternative to harmful pesticides. The promise: small devices or smartphone apps emit high-pitched sounds that are barely audible to humans, but are supposed to repel mosquitoes without poisoning or killing them. But these devices are clearly ineffective.
“The basic idea of using sound frequencies is not so stupid,” says ecologist Lühken. But this version could have the opposite effect. “Mosquitoes use wingbeat frequencies to find mates.” So he believes that ultrasonic devices attract mosquitoes rather than repel them. Effective mosquito traps that rely on sound frequencies are not yet on the market.
“I don’t think about it at all,” says consumer advocate Jorde. Instead, he recommends using mosquito nets to keep mosquitoes out indoors. He wears long clothes outside. Whether mosquitoes can detect ultrasound is controversial. American researchers have found that their hearing limit is about 2,000 hertz. Anything above 20,000 Hz is considered ultrasound.
Essential Oil and Scented Bracelet
Essential oils such as citrus or lavender can help repel mosquitoes, but only for a short period of time. “They definitely can’t compete with the chemo club, because you have to constantly cover yourself with a cloud of scent,” Jorde explains. Lühken also says that essential oils can make mosquitoes no longer recognize their host, but this only works if the oil is distributed throughout the body.
But be careful about this. Essential oils can cause serious allergic reactions in some people. In addition, applying oils all over your body will reduce sweating. Essential oils regulate body temperature, which in turn can lead to additional symptoms such as headaches, malaise, and circulatory problems.
Mosquito repellent bracelets designed to repel mosquitoes by releasing scent have proven largely ineffective. Citronella bracelets are particularly popular. Manufacturers advertise that they are waterproof, comfortable, and durable. “There’s definitely not a lot of consensus around bracelets,” says Jorde. “But mosquitoes on calves probably won’t be particularly impressed by the scent of something lingering on your wrist.”
performance
Mosquitoes are attracted to various human breaths. For example, they can detect carbon dioxide exhaled or excreted through the skin. The more CO, the more2 The more you exhale, the more likely you are to get stung. How attractive a person is to animals depends on the composition of their sweat. Several studies have shown that carboxylic acids, which are responsible for the typical sweat odor, are particularly attractive. In any case, regular showering helps.
One way to fool mosquitoes’ keen sense of smell is to stand near a fire. Mosquitoes have a hard time finding people near a grill or campfire. “If you’re covered in smoke, you’re less likely to get stung,” says ecologist Lühken. On the other hand, a robber’s cane or cigarette is less effective because the smoke comes from a specific point, says consumer advocate Jorde.
Coolant and Heat Fins
Even if you use mosquito repellent, there are a number of ways to relieve itching and swelling if you get bitten. Cooling the puncture site can help. Many roll-ons or ointments available at drug stores contain volatile alcohols that provide a short-term cooling effect.
Tristan Jorde prefers the old home remedy, ribwort, which is “happy and readily available everywhere.” The mucus has a cooling effect and relieves itching. But ribwort has other benefits, too: the tannins it contains can shrink swelling, making stings less painful. The natural antibiotic properties of the ribwort can also help prevent inflammation.
In addition to cooling, the physical opposite, heat, also helps. The so-called heat pen is Renke Lühken’s favorite. Press the stitch for a few seconds. The mobile version is especially practical for smartphones with a USB-C port. If necessary, just connect the small device to the phone.
However, it is not yet fully understood exactly how the battery-powered Stitch Healer works. The most likely explanation is that the enzymes in the mosquito saliva responsible for the itching are denatured at high temperatures, i.e., irreversibly destroyed. The small heating plate of the heat pen reaches about 50 degrees.
