Buzzing mosquitoes, itchy bites, and spray-on repellents are all part of outdoor summer “fun,” and for some of us, they’re unavoidable. If you feel as if you have a huge mosquito target on your back — or arm, or leg — it’s not in your head. Here’s why, and what you can do about it.
Why Mosquitoes Prefer Some People Over Others
“The phenomenon does exist, and you can demonstrate that scientifically,” James Logan, head of the Department of Disease Control at the London School of Hygiene and Tropical Medicine, said of the insects’ apparent preference for some people. “You can also show that’s due to body odor.”
Mosquitoes hunt using all of their senses, but smell is a predominant factor. A higher metabolism, higher body temperature and more sweat make you more likely to be bitten. But a person’s scent is just one element. Mosquitoes are attracted to the lactic acid your body produces, the carbon dioxide you exhale and the natural bacteria that live on your skin.
“The good news is that these people smell normal, so they smell like a human being,” Professor Logan said. “The bad news is that they will probably always be that level of attractiveness.”
“If we identify the genes that control the production of natural repellents and susceptibility to mosquitoes, we can develop a drug that would keep mosquitoes away rather than putting DEET on,” he said.
Keep Mosquitoes at Bay Before They Bite
The Centers for Disease Control and Prevention recommend using a repellent registered by the Environmental Protection Agency. The most popular and accessible form of E.P.A.-approved repellent is DEET, short for N,N-diethyl-meta-toluamide.
You shouldn’t be fooled by higher DEET concentrations on repellent bottles, however. Unlike the SPF rating in sunscreens, higher concentrations of DEET don’t mean more protection. Instead, the higher the percentage of DEET in a repellent, the longer it will be effective before you have to reapply.
Janet McAllister, a research entomologist for the C.D.C.’s division of vector-borne diseases in Fort Collins, Colo., recommends visiting the E.P.A.’s repellent-finder website to choose the right one for your needs.
“If you’re going to be outdoors for eight hours, you might want to try a higher concentration repellent, but if you’re only outdoors gardening for maybe an hour or two, you could use a lower concentration,” Dr. McAllister said.
And those citronella candles — do they work?
“No,” Dr. McAllister said, “not unless you’re standing directly over the candle. It’s the smoke that repels them, not the citronella.”
“They’re very hard to fool,” she added. “Even if you’re standing next to a mosquito trap, they can still tell a live animal from not.”
“We don’t recommend using higher than 30 percent of DEET for anything,” Ms. Boerner said. She and The Sweethome team tested how different repellents dried, smelled and felt on the skin. They applied some to fabric to make sure it dried quickly, didn’t leave residue and didn’t stain clothing.
Dry versions typically spray on lightly and contain a small amount of cornstarch, which leaves your skin feeling dry after application and avoids that oily sensation that comes with other repellent sprays. The downside to dry sprays, however, is that cornstarch (or talc, in some sprays) can leave a white powder on clothing, but it can be easily brushed off, Ms. Boerner said.
Dr. Mark Fradin, a clinical associate professor of dermatology at the University of North Carolina at Chapel Hill, has studied the efficacy of repellents. He recommends a three-pronged approach to prevention: avoid mosquitoes’ natural habitat, apply repellent to skin and apply repellent to clothing.
Similarly, when you’re applying repellent, don’t skimp. Many people treat it as if it has a “cloaking effect,” and that won’t protect you at all.
“A dot behind each ear or on each wrist will not set up a force field,” Dr. Fradin said. “If you skip a one-inch swath, they’ll find it.”
If you’re uncomfortable using DEET, Dr. Fradin recommends using two other repellents recommended by the C.D.C.: picaridin and lemon eucalyptus oil.
Treat Bites the Right Way
Even with preparation, you’re likely to get at least a few bites over the course of the summer, especially if you’re more prone to bites than others. When it comes to treatment, Dr. Fradin recommends ice, a low-potency hydrocortisone and simple patience.
“We try to dissuade people from using a topical Benadryl cream because of the risk of sensitivity or reaction,” he said. He also recommends staying away from caladryl and calamine lotions for the same reason. Many turn to them to alleviate itching, but these may be better options for skin irritation from something like poison ivy.
“I don’t think caladryl does much for insect bites,” Dr. Fradin said.
Should you have an intense reaction to a mosquito (or other insect) bite, prescription-strength steroids may be needed, and you should consult your doctor. You should try not to scratch, and instead gently tap the area around the bite to alleviate itching. After that, you just have to wait it out. Dr. Fradin offered one crumb of comfort.
“It will eventually stop itching,” he said.