If Mosquitoes Love You, Maybe Switch Soaps

Mosquitoes really do like some people more than others. Some of the features that make you a mosquito magnet aren’t ones you can easily alter—your body size, for example, or the natural smell of your skin. But now, a study has found that scented soaps may also make a difference, and that’s something you can easily change.

The study wasn’t large enough or comprehensive enough to tell us exactly which soaps we should be using to avoid mosquitoes (or at least to avoid attracting them), but it raises a lot of interesting questions. The researchers presented Aedes aegypti mosquitoes with a choice of two sleeves that had been worn by either people who did not wash their arm, or who washed their arm with one of four soaps—or actually, if you want to get technical, body washes. (The FDA doesn’t consider body wash to be soap, but pretty much everybody else on the planet uses the terms interchangeably, including the people who conducted this study.)

Floral scented soaps may be ones to avoid

Three of the body washes seemed to be more attractive to the mosquitoes. These were Dial Body Wash Marula Oil, Dove Deep Moisture Nourishing Body Wash, and Simple Truth Organic Honey Blossom Baby Shampoo & Body Wash. All three had floral scents, suggesting that mosquitoes may find these smells tastier than the scent of unwashed human skin. When mosquitoes aren’t drinking our blood, they do actually sip flower nectar—so that makes sense.

That said, the mosquitoes were reacting to the scent of the sleeves, without human volunteers present. That’s one of the unanswered questions: whether they might stop caring about the floral scent when faced with a person’s hot, tasty breath (they sniff out carbon dioxide to find us).

Somewhat unsurprisingly, chemical analysis found that people smell different after washing with a scented soap. But it wasn’t just a matter of smelling like a person plus a body wash; washing our skin seems to reduce some of our natural smells while adding some new scents from the soap. The researchers tested two typical consumer body washes (Dial and Dove) as well as two brands that claim to be more “natural” (Simple Truth and Native), finding that the natural brands did have fewer chemical compounds. But one of them (the Simple Truth product) was still in the group of soaps that were more attractive to mosquitoes.

What might keep the mosquitoes away

The fourth soap, the one that made volunteers’ scent less attractive to the mosquitoes, was Native Coconut and Vanilla Body wash. Does this mean coconut scents keep mosquitoes at bay? It’s possible, but more research is needed to find out whether this one product is an outlier or if there is a pattern to be found with coconut-scented soaps, “natural” brands of soaps, or perhaps some other factor entirely. The researchers did not test an unscented soap, which would have been interesting to compare.

By the way, we also don’t know whether these findings apply to all mosquitoes. Aedes aegypti mosquitoes, used in this study, are found in the southern U.S., as well as parts of the Midwest and along the west coast. These mosquitoes can carry Zika, dengue, and yellow fever viruses, so they are of particular interest to scientists. No word on whether the various species of Culex mosquitoes, which are more widespread in the northern U.S., share the same preferences.

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