Why Mosquitoes Bite Some People More Than Others

Did you know that mosquitoes seem to prefer some people over others? They don’t just bite randomly. Female mosquitoes (the ones that actually bite) are drawn to humans because of a mix of factors like body heat, carbon dioxide, and odors that come from our skin. These smells are affected by things like genetics, the bacteria on our skin, and even what we eat.

How Mosquitoes Detect Humans

Mosquitoes rely on several senses to locate people. They use vision, body heat, and their keen sense of smell, which is powered by multiple olfactory organs (like their antennae and proboscis). These organs contain up to 80 types of olfactory sensory neurons (OSNs), and their brain processes these signals to locate a human.

The key to mosquito-human attraction lies in “kairomones.” These are chemical scents that humans produce, often through sweat and breath. The human scent includes a mix of hundreds of substances, such as carbon dioxide, lactic acid, ammonia, and organic fatty acids.

Mosquitoes first detect CO₂, exhaled in our breath, from as far as 30 feet away. This acts as their long-range “radar.” Close up, body heat and specific odors guide them to their target. Interestingly, one mosquito species, Aedes aegypti, has sensory neurons that can detect multiple odors at once. This makes them especially skilled at picking up the right mix of human scents.

What Research Says About Mosquito Preferences

Back in the 1950s, researchers did experiments using human-shaped water containers dressed in clothes. They learned that mosquitoes were more likely to land on warm surfaces, those releasing carbon dioxide, or clothes soaked in human sweat. These studies also revealed that mosquitoes prefer human smells over animal ones.

More recent studies show that skin bacteria play a big role. According to Meg Younger, a neuroscientist at Boston University, “Our skin is covered in bacteria that emit volatiles that vary from person to person. This difference in odor between people accounts for the difference between the attraction of mosquitoes to different people.”

Mosquitoes pick up these smells using special sensors in their antennae. Some human compounds, especially aldehydes, trigger strong signals in mosquitoes’ brains. These signals are what help them find humans even from far away.

Why Some People Attract More Mosquitoes

Several factors can make someone more appealing to mosquitoes. These include genetics, diet, and environmental conditions. For instance:

• Exercise: Working out increases lactic acid levels in sweat, which mosquitoes love.
• Pregnancy: Pregnant women tend to have a higher body temperature and metabolic rate, making them more attractive to mosquitoes.
• Skin Bacteria: Different skin microbiota can affect how you smell to mosquitoes.

Certain genetic markers in humans also determine the chemical makeup of your scent. This includes compounds like sulcatone, which can either attract or repel mosquitoes depending on its concentration.

Mosquito-Borne Diseases (MBDs)

Female mosquitoes bite humans to gain the protein needed for laying eggs. However, during this process, they can transmit dangerous pathogens like viruses and parasites. MBDs, such as malaria, dengue, Zika virus, and West Nile virus, account for 17% of infectious diseases worldwide.

Malaria alone causes over 200 million infections and 400,000 deaths each year—primarily in sub-Saharan Africa. Similarly, diseases like Zika and dengue have significant health and economic impacts, leading to illness, death, and high medical costs.

Some pathogens even manipulate mosquito behavior to increase their spread. For example, Plasmodium (the parasite behind malaria) changes the infected person’s scent, making them more attractive to mosquitoes at a stage when the parasite is ready to spread.

Fighting Mosquitoes

Scientists are developing methods to reduce mosquito populations and prevent bites. Some focus on targeting mosquitoes’ sense of smell. According to Professor Meg Younger from Boston University, as we learn more about how mosquitoes detect odors, we can create better repellents and traps.

Here are some current strategies being explored:

• Repellents like DEET and lemongrass oil mask human scent.
• Traps lure mosquitoes using attractants and chemicals that kill them or their larvae.
• Gene-editing tools like CRISPR may one day suppress mosquito populations by altering genes that affect their ability to sense humans.

Dr. Anandasankar Ray of the University of California, Riverside, highlights that affordable “mask” and “pull” strategies could offer solutions in areas heavily affected by MBDs.

Final Thoughts

Some people are more attractive to mosquitoes due to specific scents linked to genetics, diet, and other personal factors. Understanding why mosquitoes bite certain people can help guide strategies for personal protection and mosquito control.