By numbers alone, the mosquito is the deadliest animal on the planet. They spread diseases like malaria, yellow fever, dengue fever, Zika virus, and West Nile virus. Even if you’re not worried about diseases, there’s no reason to put up with the tiny little bloodsuckers. They’re incredibly annoying, and for most people, itchy red bumps are reason enough to invest in bug spray. Few things can ruin a picnic as quickly as mosquitoes. So what we can do? Are there natural alternatives to products loaded with DEET and other synthetic chemicals? Can we really load up on certain houseplants to reduce our exposure to bug bites? And do those citronella torches really work? We spoke with Joe Conlon, the technical advisor of the American Mosquito Control Association, to find out how we can banish mosquitoes from our homes once and for all.
Is DEET a safe mosquito repellent (and how does it compare to alternatives)?
“Let’s face it,” Conlon tells HealthyWay, “DEET is the gold standard by which all other repellents are judged. It’s by far the most prevalent repellent out there.” N,N-Diethyl-meta-toluamide, better known as DEET, is a synthetic chemical that seems to work by blocking the receptors in mosquitoes’ antennae. They’re then unable to locate humans and therefore unable to bite us. “There are over 500 DEET products that are registered by the EPA,” Conlon says. “If you’re going to go the DEET route, I would suggest a 25 to 30 percent formulation. That’s both repellent for ticks and mosquitoes. And that will give you a good solid four to eight hours of protection.” If you’re worried about the safety of DEET, you’re not alone. In the early 2000s, several reports indicated that young children were having seizures when exposed to products with high concentrations of DEET. A 2003 study found no evidence of toxicity, however, and concluded that “the suggestion that young children are more prone than adults to the neurotoxic effects of DEET is not supported by critical evaluation of existing evidence.” If you’re wondering about using DEET during pregnancy, that too appears to be safe. One study followed pregnant women in Thailand who used DEET; it found no adverse effects in the women or in the babies. More recently, a 2013 study found no evidence that DEET was dangerous to humans in typical concentrations. The scientific consensus on DEET’s safety is pretty clear, but we’ve got another issue with it: It feels weird and smells bad. “In the past, DEET has had some cosmetic issues,” Conlon admits. “The manufacturers have seen this as an issue, and there are formulations that don’t have any of those bad cosmetic things anymore. But some people just don’t like it—and that’s fine.” Conlon says that another synthetic ingredient offers similar mosquito protection: picaridin. While it’s not a natural mosquito repellent, it’s pretty close. “It’s the most widely sold repellent in the world outside of the United States, and it’s very good,” Conlon explains. “It’s got a very light feel, it doesn’t smell bad, and it’s a synthetic derivative of pepper plants, so that’s kind of an organic pedigree. I’d suggest that your readers look for products with a 15 to 20 percent formulation of picaridin.” Research indicates that picaridin is roughly as effective as DEET, although the authors noted that different mosquito species might respond differently to varying active ingredients.
Natural Mosquito Repellents: What to Know About Alternatives to DEET
Let’s say that you want to avoid DEET simply because you don’t like it, and you’re looking for some sort of completely natural mosquito repellent. That’s perfectly fine, but most of the natural repellents approved by the EPA aren’t quite as effective. The good news: If you’re willing to reapply your repellent every once in a while, you can get the same basic effect. “Citronella oil is repellent, a bona fide repellent,” Conlon says, “but it’s a mild repellent. The current formulations out on the market give you about one hour of protection. And that’s one hour more than you’ll get if you don’t use any type of protection, but I’m afraid it’s far poorer than anything you would get with any of the other [active ingredients] that are marketed.” One study found that citronella oil could work for up to two hours—which really isn’t great, all things considered. Unfortunately, that same study found citronella oil to be a more effective option than various other essential oils. Patchouli and clove oil provided similar levels of protection, but before you start building your own DIY natural mosquito repellent with those substances, remember: Natural doesn’t mean safer. “Clove oil is a repellent if you get purified oil, and it will repel mosquitoes,” Conlon says. “At that purified level, it doesn’t smell like cloves, [but] it will burn a hole right through your skin. It’s extremely corrosive. A lot of nefarious groups will market these chemical concoctions that contain clove oil and say, ‘It’s a known repellent of mosquitoes.’ Well, that’s true, but not at the concentration they’re using.'” It’s not all bad news for naturopaths. Oil of lemon eucalyptus is a useful natural alternative, although the Centers for Disease Control and Prevention warns that parents shouldn’t use it on children 3 years of age or younger. “DIY mosquito repellents that use oil of lemon eucalyptus as one of their main ingredients will be the most [effective], since the oil is almost as effective as 25 percent DEET,” says Karen Thompson, editor of pest control blog InsectCop. “However, since lemon eucalyptus mosquito repellents work for no more than six hours, depending on their potency, you’ll need to reapply often. I’d advise reapplying this type of insect repellent every two to three hours.” Thompson recommends mixing oil of lemon eucalyptus with a neutral oil (such as soybean or olive oil) and alcohol. To reiterate, though, this natural repellent isn’t appropriate for young children. Test for sensitivities before spraying it all over your skin by putting a small amount on your wrist or another non-sensitive area. Conlon notes that oil of lemon eucalyptus isn’t technically as effective as DEET, but he still thinks it’s a valid alternative. “I’m not quite sure people could tell a difference,” he says. “There’s a difference in, maybe, 86 percent repellency versus 95 percent repellency. Whether a person could notice that or not, it’s difficult to say. But it’s a natural alternative for people who want a natural product.” Catnip oil is also effective, but only when refined and concentrated. “There’s a formulation of catnip oil called refined oil of Nepeta cataria,” Conlon says. “It’ll give you seven hours of protection… I’ve never used it myself, but it’s a bona fide repellent registered by the EPA.” Conlon says that the USDA is currently looking at breadfruit—apparently, its smoke is an excellent repellent—and other natural repellents, but currently, there’s not many tried-and-tested options. “There’s a huge amount of research going on to find natural insecticides and natural repellents because the public is really looking for them,” he says. “Whether we’re ever going to be able to find [a perfect natural mosquito repellent], I don’t know. …A lot of people are under the impression that nature has provided us with the answer. Nature might—but there’s no evolutionary pressure for plants to produce something like that.”
Get rid of mosquitoes around your house.
We were excited to read about natural mosquito-repellent plants, so we asked Conlon what we should start planting. Unfortunately, he says that “there aren’t any plants that are going to provide any level of protection at all. Citronella, which is effective, is derived from [different species of lemongrass], but you have to crush the leaves in order to get the oils out.” As for lemongrass, Conlon says, “If you plant lemongrass all over your yard, you’re not really going to repel anything. The wind currents will waft off any volatilization of the chemicals inside the plants. Unfortunately, there’s no silver bullet in that regard.” For a second opinion, we asked Thompson to weigh in. “Plants like lemongrass, lavender, basil, marigolds, garlic, and peppermint will be unpleasant for mosquitoes, and therefore, they will be less likely to visit the area where these plants grow,” she says. “But these mosquito-repelling plants don’t automatically mean no mosquitoes.” In other words, planting these types of plants won’t hurt your cause, but it probably won’t help much, either. Well, at least we’ve got those citronella torches. Speaking of which—do those things actually work? Sort of. Citronella oil is a real repellent, but Conlon says that commercial citronella oil candles don’t contain enough of the substance to do much of anything. Any sort of smoke will drive mosquitoes away, but you’ll have to be fairly close to the flame to enjoy any benefit. A better option is a simple house fan, which will blow the weak-flying insects away while dissipating the carbon dioxide and chemical signals from your body, effectively masking you.
Easy Ways to Get Rid of Mosquitoes
Besides plants, there are a few things you can do around your backyard to keep it skeeter-free—or at least less enticing for them. “Obviously, drain any type of standing water,” Conlon says. “If you have ditches that fill with water, make sure that they’re clean, so that the water flows freely. Mosquitoes will not lay their eggs in water that’s flowing, but stagnant water is fair game for them.” He continues, “If you’ve got low-lying areas on your property that fill with water after heavy rains, it’d be good to fill those in because there are mosquitoes that breed specifically in those kinds of low-lying depressions. They lay their eggs in the dirt, and when the water comes and covers them, they hatch. They can withstand a drought for three to five years.” Look for containers with standing water and empty them out. Don’t worry about putting insecticides in them, but wipe down the sides and clean them with soap and water; some mosquito species lay eggs just above the waterline, so thoroughly scraping the sides of a container will help to prevent infestations. “It takes a minimum of five days for a mosquito to go from an egg to an adult,” Conlon says. “If you empty containers every five days, you’re good to go.” Check evaporation pans, leaky faucets, and any other place where water might build up over time. Mosquitoes don’t need much water to do their thing. “When I was in South America doing research, I found Aedes aegypti, the Zika mosquito, breeding in Coke bottle caps,” Conlon says. “It’s incredible. You’ve got to have a lot of respect for mosquitoes.” Once you’ve eliminated standing water, look for ways to prevent the skeeters from making their way into your home. “People should maintain their window screens,” Conlon says. “If you’ve got any vents to the outside, bathroom vents, things like that, I would suggest putting some hardware cloth or screening over the vent on the outside. Mosquitoes can and will get in through those vents. They’ve done it in my house—I learned the hard way.” Getting completely skeeter-free will require multiple steps: Carefully evaluate your home and yard, try out different repellents, and use traps and zappers to reduce mosquito populations around your area. If you’re sticking with natural products, research them carefully. Conlon recommends following EPA guidelines when protecting yourself from mosquitoes. “Some of the nastiest diseases on the planet are a seven-hour plane flight away,” he says. “Zika and West Nile virus should’ve convinced us that we need to be prepared for diseases for which we have no historical antecedent. People need to be very serious in terms of what they’re using in terms of mosquito control methods and repellents. That’s why I say stick with the EPA. Stick with the stuff that we know, because it could be a matter of life or death.”