The familiar, high-pitched whine is the unwelcome soundtrack of summer evenings. As you gather with friends on a terrace, a common scene unfolds: one person becomes the main course for every mosquito in the vicinity, while others remain virtually untouched. The age-old explanation often offered is that the unlucky individual has “sweet blood.” But science tells a very different story, debunking this and many other myths about why mosquitoes target us and how we can stop them.
The Myth of Sweet Blood: What Really Draws Mosquitoes In
Mosquitoes are not attracted by the taste of your blood. By definition, they cannot know what your blood tastes like before they have pierced your skin. The real attraction begins much earlier, from dozens of meters away. Mosquitoes are highly sensitive to carbon dioxide (CO2), the gas we exhale with every breath. This plume of CO2 acts as a long-range beacon, alerting the insects to a potential meal.
As they get closer, their selection process becomes more refined. They begin to detect body odor, specifically components in our sweat like lactic acid. This is how they distinguish humans from other animals and, crucially, how they choose their preferred targets within a group.
Research has shed light on this selective process. Scientists projected the body odors of different individuals onto heated discs and observed mosquito landing preferences. The results, reported by National Geographic, revealed a strong attraction to carboxylic acids. These fatty acids, present in human sweat and sometimes compared to the smell of rancid butter or cheese, are a powerful lure. These acids are also produced by beneficial microbes living on our skin, which additionally create a substance called acetoin that mosquitoes find appealing. Hormonal factors related to age or pregnancy can further alter a person’s scent profile, making them more or less attractive.
Can Changing Your Diet or Soap Deter Mosquitoes?
Since body odor is a key factor, the logical question is whether we can change our scent to become less appealing. The answer is complicated. A significant part of our body odor is determined by our genetic makeup, which is impossible to alter radically, according to the French National Institute of Health and Medical Research (Inserm).
Minor dietary adjustments might have a marginal effect. Some research suggests that eating fewer bananas or drinking less beer could help, but there is no evidence that consuming garlic or vitamin B attracts mosquitoes, so altering their intake is useless. The idea of using a specific soap is another popular strategy, but it comes with no guarantees. A 2023 study from American universities found that the effectiveness of a soap depends on the unique chemical reaction between the soap, an individual’s sweat, and their skin microbiome. Surprisingly, a soap marketed as a repellent could actually create a scent that attracts mosquitoes when mixed with a person’s natural odor. Neuroethologist Clément Vinauger explained to National Geographic that while most soaps tested contained limonene, a known mosquito repellent, three out of four soaps ended up making users more attractive to the insects.
From DEET to Ultrasonic Waves: What Truly Works
When it comes to reliable protection, repellents containing DEET remain the most effective option, though they can cause eye irritation and are not recommended for young children or pregnant women. In areas with less aggressive mosquito populations, natural solutions such as those based on lemon eucalyptus oil can be a viable alternative.
However, the market is flooded with gadgets that promise a high-tech solution, with no evidence to back up their claims. Smartphone applications that claim to emit low-frequency sounds to repel mosquitoes are a prime example. The theory is that these sounds mimic the wingbeats of male mosquitoes to repel biting females, or imitate dragonflies, a natural predator. Inserm’s review of ten robust scientific studies found no proof that these apps work. It is likely that any sound potentially audible to female mosquitoes is beyond the capability of a standard phone speaker to reproduce accurately.
Similarly, ultrasonic devices and anti-mosquito bracelets have been shown to be ineffective. A television experiment by “Envoyé spécial” in June 2025 demonstrated that a bracelet did nothing to prevent mosquito bites. The scientific consensus is clear: these fashionable gadgets offer no real protection.
The Itch: Why Scratching Makes It Worse
Once bitten, the immediate urge to scratch is powerful, but it is the worst possible response. Scratching a mosquito bite does not provide relief; it aggravates the inflammation caused by the insect’s saliva. It can tear the skin and significantly increase the risk of infection, even though some recent research has suggested it might temporarily boost the local immune barrier. The most effective way to soothe a bite is to clean and disinfect the area, and then apply an ice cube. The cold temperature is a simple and effective way to reduce the itching sensation.
