Want to avoid mosquito bites? Step away from the beer

For three hot days in August 2023, at one of the biggest music festivals in the Netherlands, a line of people snaked outside the entrance of four welded-together shipping containers. But they weren’t waiting to watch a performance or get Billie Eilish’s autograph. 

They were queuing up to meet some mosquitoes. 

The shipping containers were a pop-up laboratory, and the people were volunteering for a study that gauged how alluring they were to the blood-sucking insects. Festivalgoers rested their arms against acrylic boxes that let caged mosquitoes smell but not bite. A camera helped track the insects’ landings, and then a computer calculated a score.

“You’d hear loud cheers when a score popped up on the scoreboard,” says Felix Hol, a quantitative biologist at Radboud University Medical Center in Nijmegen, the Netherlands. People tried to prove that they were more appealing to mosquitoes than their partners, says Hol’s colleague, Sara Lynn Blanken. They’d see their score and say, “‘You see, I’m right!’”

The team’s Mosquito Magnet Trial offered an unusual attraction for people attending the 2023 Lowlands festival in Biddinghuizen; it also served up some buzz-worthy science. Certain behaviors seemed to influence people’s attractiveness to mosquitoes, the team reported August 26 at bioRxiv.org. Drinking beer, smoking weed and sleeping close to someone tended to boost people’s magnetism, the team found. Wearing sunscreen did the opposite.

The study adds to the relatively little that’s known about mosquito biting preference. Previous studies have identified some factors that influence a mosquito’s taste, but no one knows exactly what goes into selecting a target. There’s probably an interplay of different elements at work, like someone’s diet, odor, temperature and the microbial companions living on their skin, Hol says.

In the pop-up lab, Hol’s team tested mosquitoes’ responses to volunteers and collected a slew of other data, including info about their hygiene, diet, drug and alcohol use, sleeping habits and sunscreen application. For the researchers, the experiment meant nearly nonstop action. They’d set up the lab at 9 a.m., work till 10 p.m., attend the festival and collapse into their tents at night. Then, they’d wake up and do it all over again.

One reason for the long hours was the sheer amount of interest in the team’s experiment. “There were never less than 20 people in front of the door,” Hol says. “I was really completely overwhelmed by the enthusiasm for the project and for science in general.”

The team tested over 500 volunteers and observed a wide range of mosquito responses. After some people placed their arm against the cage, the insects zipped away to the sugar feeder on the opposite side. Other participants had mosquitoes homing in on them within seconds.

Such extra-enticing humans may have been beer drinkers. People who recently drank the brewed beverage were 44 percent more attractive to mosquitoes than people who abstained, the team found. That number factored in how many times the insects landed on the side of the cage pressed against a volunteer’s arm. The researchers saw a similar link in people who used cannabis and people who had slept near another person the previous night. But sunscreen seemed to swat away mosquito interest: Among people who had showered recently, those who had applied sunscreen were about half as attractive as those who had not, the team found.

Hol recommends taking the results with a grain of salt. Because of the study’s location, it was more loosely controlled than previous efforts. And the study participants, mostly camping-enthused festivalgoers, may not represent the average population.

Overall, though, the team’s results suggest that if you don’t want to get bitten by mosquitoes, “don’t drink beer, don’t smoke weed, don’t sleep with people and put on your sunscreen,” Hol says. If that advice doesn’t sound appealing, he says, there is an alternative: “You can do whatever you want and put on long sleeves.”