Do mosquitoes love you? What they really adore might be the scent of your soap.
That’s the conclusion drawn from a small study published in the journal iScience, which tested how much mosquitoes were attracted or repelled by four different brands of body wash:
- Dial Body Wash Marula Oil
- Dove Deep Moisture Nourishing Body Wash
- Simple Truth Organic Honey Blossom Baby Shampoo and Body Wash
- Native Coconut and Vanilla Body Wash
The study was tiny, involving just four volunteers. Using all of the body washes in succession, each person lathered and rinsed just one arm, then wore nylon sleeves on both arms for an hour to concentrate the aromas (including their natural body scent).
After that, researchers removed the sleeves and placed them inside a mesh cage full of mosquitoes to see which scents most attracted or repelled the insects.
Could Certain Scents Keep Mosquitoes at Bay?
All four body washes contain limonene, a known mosquito repellent derived from citrus. But only one soap — the one scented with coconut — consistently repelled insects in this experiment.
“Coconut oil derivatives are strongly repellent to mosquitoes,” says senior study author Clément Vinauger, PhD, an assistant professor of biochemistry at Virginia Polytechnic Institute and State University in Blacksburg.
The researchers found that several other chemicals in the body washes appeared to repel mosquitoes, but the effect wasn’t as consistent as it was for coconut.
“Based on our analysis, the combination of benzyl benzoate, gamma-nonalactone, and benzaldehyde [all coconut-derived ingredients] was significantly associated with reduced mosquito attraction,” Dr. Vinauger says. “It is possible that the combination of these coconut-related chemicals and those we identified all contribute to repelling mosquitoes.”
Because the study wasn’t designed to test coconut oil or isolated chemicals on their own, it’s not yet clear which specific ingredients or combinations of ingredients might be most effective for repelling mosquitoes, or which ones might have the opposite effect, the researchers wrote.
It’s also unclear whether coconut or other chemicals might have specific mosquito repelling properties on their own, or only when applied to the skin via soaps, or through other applications such as sprays on skin or clothing.
There Are Hundreds of Mosquito Varieties in the U.S.
Beyond the study’s small size and focus on only a few different soaps, another limitation of the research is that the experiments only used Aedes aegypti mosquitoes. There are more than 200 types of mosquitoes in the United States, according to the Centers for Disease Control and Prevention.
Still, there are two reasons why the Native Coconut and Vanilla Body Wash might have had unique mosquito repellent properties in the study, says Floris van Breugel, PhD, an assistant professor of mechanical engineering at the University of Nevada in Reno, who studies how odors attract insects. Dr. Breugel was not involved in the current study.
One possibility is that the Native soap disrupted the natural human scent (which generally attracts mosquitoes) more than the other soaps tested, leading it to be a more potent insect repellent, says van Breugel. Another possibility is that the known insect repellent in the Native soap played an outsize role in deterring mosquitoes.
“Crucially, there is no clear evidence that supports the notion that coconut or vanilla smells contribute to the aversive nature of that soap,” van Breugel says. “I also don’t believe there is anything more ‘natural’ about the Native[-brand] soap compared to the others, considering the volatile chemicals they discuss as being abundant in each soap.”
For now, it doesn’t make sense to pick a soap based on its potential to repel mosquitoes, van Breugel adds. Even when soaps contain compounds known to repel mosquitoes, these compounds aren’t always among the ingredients listed on the labels. And when these compounds are listed, it’s still not always clear how much is in the soap or whether it’s enough to effectively repel mosquitoes.