Editor's note: This story was originally published in 2016 and has been updated.
People do the darnedest things in hopes of avoiding mosquito bites. They burn cow dung, coconut shells or coffee. They drink gin and tonic. They eat bananas. They spray themselves with mouthwash or slather themselves in clove/alcohol solution. And they rub themselves with Bounce. "You know, those heavily perfumed sheets you put in your dryer," says Dr. Immo Hansen, professor at the Institute of Applied Biosciences at New Mexico State University.
None of those techniques have been tested to see if they actually keep mosquitoes away. But that doesn't stop people from trying them, according to a study that will be published this summer by Hansen and colleague, Stacey Rodriguez, lab manager at the Hansen Lab at NMSU, which studies ways to prevent mosquito-borne diseases. They and colleagues asked 5,000 people what they did to protect themselves against mosquitoes. Most used conventional mosquito repellents.
Then researchers asked about their traditional home remedies. That's when the cow dung and dryer sheets came out. In interviews, Hansen and Rodriguez shared some of the responses they received. Their paper has been published in the peer-reviewed journal PeerJ.
Beyond folklore and traditional remedies, there are proven ways to protect against mosquitoes and the diseases they carry. NPR talked with researchers, many of whom spend lots of time in mosquito-infested jungles, marshes and tropical areas.
Which repellents work best to stop mosquitoes from biting?
Products containing DEET have been shown both safe and effective. DEET is shorthand for the chemical N,N-diethyl-meta-toluamide, the active ingredient in many insect repellents. A 2015 article in the Journal of Insect Science examined the effectiveness of various commercial insect sprays, and products containing DEET proved effective and relatively long lasting. Rodriguez and Hansen were authors of the 2015 study, and replicated the results in a 2017 article in the same journal.
DEET appeared on store shelves in 1957. There was some early concern about its safety — speculation that it was linked to neurological problems. But recent reviews, for example a study published in June 2014 in the journal Parasites and Vectors, says, "Animal testing, observational studies and intervention trials have found no evidence of severe adverse events associated with recommended DEET use."
DEET isn't the only weapon. Products containing the active ingredients picaridin and IR 3535 are as effective, says Dr. Dan Strickman, with the Global Health Program at the Bill and Melinda Gates Foundation (which is a funder of NPR) and author of Prevention of Bug Bites, Stings, and Disease.
Repellents with any of those active ingredients are recommended as safe and effective by the Centers for Disease Control and Prevention. They are widely available around the world.
Actually, Strickman gives the edge to picardin.
"Picaridin is a little more effective than DEET and seems to keep mosquitoes at a greater distance," he says. When people use DEET, mosquitoes may land on them but not bite. When they use a product containing picaridin, mosquitoes are less likely to even land. Repellents with IR 3535 are slightly less effective, Strickman says, but they don't have the strong smell of other products.
Then there is oil of lemon eucalyptus, or PMD, a natural oil extracted from the leaves and twigs of the lemon-scented gum eucalyptus plant, also recommended by the CDC. PMD is the ingredient in the oil that makes it repellent to insects. NMSU researchers found that a product containing oil of lemon eucalyptus was about as effective and as long lasting as products containing DEET. "For some people, there's a stigma to using chemicals on their skin. They prefer a more natural product," says Rodriguez.
One surprising finding in 2015 was that a perfume, Victoria's Secret Bombshell, was a pretty good repellent. Hansen and Rodriguez said they added it to the products they tested as a positive control, believing its floral scent would attract mosquitoes. It turned out bugs hated the smell.
Their more recent 2017 study also held a surprise. A product called Off Clip-On attaches to clothing and contains a cartridge containing the area repellent, metofluthrin, also recommended by the CDC. The wearable device is designed for someone sitting in one place, like a parent watching a softball game. The person switches on a small battery-operated fan that blows a small fog of repellent into the air immediately surrounding the clip-on wearer. "It actually worked like a charm," says Hansen. It was about as effective as DEET or oil of lemon eucalyptus at keeping the bugs away, he says.
Are there products that just don't work?
Not all products deliver what they promise. The 2015 study found vitamin B1 skin patches to be ineffective at repelling mosquitoes. The 2017 study added citronella candles to the list of products that don't keep mosquitoes away.
So-called bug-repellent wristbands and bracelets fail to repel mosquitoes, according to the recent study. These products contain a variety of oils including citronella and lemongrass.
"I've had mosquitoes land right on the bracelet that I was testing," says Rodriguez. "They market [the wristbands and bracelets] as protecting you against Zika [a virus spread by mosquitoes that, in pregnant women, can result in serious birth defects], but they're completely ineffective."
Ultrasonic devices, using tones people can't hear but marketers claim mosquitoes hate, don't work, either. "The sonic device we tested had no effect," says Hansen. "We've tested others before, too. None of them work. There's no scientific evidence that mosquitoes are repelled by sound.
How often should you reapply a repellent?
Generally, it's a good bet to follow the manufacturer's instructions, experts said. People who will be outside for an hour or two should be protected with, say, a product that contains a lower concentration of DEET (about 10 percent — identified on the label). Those who will be out in the woods, or jungle or marshland, should use a higher concentration of 20 to 25 percent, and refresh every four hours or so, says Dr. Jorge Rey, interim director of the Florida Medical Entomology Laboratory in Vero Beach. "The higher the concentration, the longer it lasts," says Rey.
And again, follow manufacturer's directions on the amount used. "A lot of people think that if a little is good, a lot is better," says Dr. William Reisen, professor emeritus at the School of Veterinary Medicine at the University of California, Davis. "You don't have to take a bath in the stuff."
What kind of clothing helps protect against bites?
When Rey goes on research trips to highly infested areas, like the Florida Everglades, he suits up. "We wear long pants and long-sleeved shirts," he says. "If it's particularly bad, we use hats with nets coming down over the face. And we depend on repellent on exposed areas." That could mean hands, neck and face. But don't spray the face, experts say. To avoid irritating the eyes, put the repellent on hands and rub it on the face.
And don't forget the feet. Mosquitoes have quirky olfactory preferences. Many of them, especially the Aedes variety that transmits the Zika virus, love the smell of feet.
"Wearing sandals isn't a good idea," says Rodriguez. Shoes and socks are called for, and tucking pants into socks or shoes helps keep mosquitoes from getting inside clothing. She wears long pants when outdoors in mosquito territory — and definitely not yoga pants. "Spandex is very mosquito friendly. They bite through it. I wear baggier pants and long sleeved shirts, doused in DEET."
What else can reduce the risk of mosquito bites?
Mosquitoes can bite at any time of day, but the Aedes aegypti species that transmits Zika prefers midmorning and early evening, says Strickman. If possible, stay indoors in screened-in or air-conditioned buildings during those times.
Since these particular mosquitoes breed in standing water in containers like plant pots, old tires, buckets and trash cans, people should rid their immediate area of things that can collect water. "Swimming pools, unless they're abandoned, are OK," says Rey. The chemicals used to keep pools safe for swimming also keep mosquitoes away. It takes some close looking to find every possible breeding ground for mosquitoes. "I've seen some developing in a film of water next to a sink, or in the bottom of a glass people use to brush their teeth," says Strickman. Cleaning up areas of standing water can greatly reduce the number of mosquitoes.
The more people do that kind of basic cleanup, the fewer mosquitoes there will be. "It may not be perfect, but you'll lower the number of mosquitoes tremendously," says Strickman.
What's on the horizon to help people avoid mosquito bites and the diseases they bring?
Hansen says his lab is working on a technique in which male mosquitoes are sterilized with radiation, then released into the environment. They mate with females who lay eggs, but the eggs never hatch. The technique would target specific species, like the Aedes aegypti that transmit Zika, dengue fever and other diseases.
And a team of scientists in Massachusetts is working on a mosquito repellent that will stay on the skin and remain effective for hours or even days, says Dr. Abraar Karan, physician at Brigham and Women's Hospital. He is one of the creators of Hour72+, which he says cannot penetrate the skin and enter the blood stream — and only wears off through natural skin shedding.
Hour72+ won the Dubilier $75,000 Grand Prize in this year's annual Harvard Business School's New Venture Competition. Karan plans to further test the prototype, which is not on the market, to see how long it remains effective.
FAQs
How much DEET is needed to repel mosquitoes? ›
Products with 10% to 35% DEET will provide adequate mosquito protection under most conditions - concentrations should be based on the duration of protection needed (e.g., for 1-2 hours use <10%, for 2-5 hours use 20%); For protection against ticks, at least 20% is necessary.
Why did they ban DEET? ›DEET-related health problems include skin rashes and scarring in adults and, in a few cases, reports of neurological problems in children. A ban would affect products that are more than 30 percent DEET. New York is the first state to propose such a ban.
Does gin and tonic keep mosquitoes away? ›"You can enjoy your gin and tonic, but just don't expect it's going to stop you being bitten by mosquitoes." Quinine isn't present in tonic water in concentrated enough amounts, and in any case, says Webb, it was used to treat malaria not repel mosquitoes.
What is the most effective natural mosquito repellent? ›- Geraniol (found in citronella, lemongrass, and rose oil). ...
- Catnip oil. ...
- Cinnamon oil. ...
- IR3535.
DEET concentrations higher than 30% are not more effective and the chemical (which is absorbed through the skin) in high amounts can be toxic. Follow the directions on the label.
What percentage of DEET is most effective? ›Concentrations of DEET range from 10 percent (for about two hours of protection) to 100 percent (up to 10 hours). Maximum protection is achieved at 30% DEET formulations—higher concentration levels simply make your protection last longer.
Is DEET cancerous? ›Researchers have not found any evidence that DEET causes cancer in animals or humans. DEET has been classified by the United States Environmental Protection Agency (U.S. EPA) as "not classifiable as a human carcinogen", which means that there is not enough evidence to say that it does or does not cause cancer.
Who should not use DEET? ›The American Academy of Pediatrics recommends against using DEET products in infants under 2 months old. And while there aren't reports of issues in pregnant women, DEET hasn't been specifically studied in that group, Dr. Kassouf says.
What problems does DEET cause? ›Occasionally, there have been reports of people having negative reactions after excessive use of repellents containing DEET. These effects included seizures, uncoordinated movements, agitation, aggressive behavior, low blood pressure, and skin irritation.
What can I drink so mosquitoes don't bite me? ›Lemongrass contains an oil called citronella, a common mosquito repellent. Swap your summer glass of lemonade for a chilled glass of lemongrass tea or carefully use lemongrass oil on your skin for a quick mosquito repellent.
What can I take so mosquitoes don't bite me? ›
- DEET.
- Picaridin (known as KBR 3023 and icaridin outside the US)
- IR3535.
- Oil of lemon eucalyptus (OLE)
- Para-menthane-diol (PMD)
- 2-undecanone.
Mosquitoes hate the smell of lavender, citronella, clove, peppermint, basil, cedarwood, eucalyptus, peppermint, lemongrass and rosemary. They also hate smells such as smoke, for further insight, see our exploration on, does smoke keep mosquitoes away?
What smell do mosquitoes hate? ›Certain Natural Scents
Mosquitoes are turned off by several natural scents: cinnamon, peppermint, cedar, citronella, lemongrass, patchouli, catnip, lavender, and more. Find a favorite, and use it when you want to spend time outside.
Dryer sheets are designed to provide a pleasant scent to laundry, not to repel insects, so any insect-repellent properties may wear off quickly. In summary, while some people claim that dryer sheets can repel mosquitoes, there is little scientific evidence to support this claim.
What can I put in my yard to keep mosquitoes away? ›Plant Mosquito-Repelling Plants
Flowers like marigolds and calendula, along with herbs like rosemary, mint and lemongrass, can also keep biting insects away from the yard. Plant them near your patio or deck for the best benefit. Learn how to grow herbs in your garden.
"DEET is very safe when used properly," Rodriguez says. For everyday needs, you can use 10% or 20% DEET to avoid mosquito bites. "Higher concentrations of DEET such as DEET 100% are only necessary in places with high mosquito density and risk for mosquito-borne illness," Rodriguez says.
Is DEET banned in Europe? ›No, as part of the regulatory process 100% DEET products are now being withdrawn throughout the European market and will no longer be available. DEET repellents over 50% in strength will not be legal for sale in the EU after 2016.
Is 100% DEET harmful to humans? ›The human health risk assessment concluded that there are no risks of concern because no toxic effects have been identified when used as a dermally applied insect repellent, and there is no dietary or occupational exposure for DEET.
Is anything better than DEET? ›For more than 50 years, DEET has reigned as the undisputed champion of insect repellents. No longer. There's now a potentially better alternative on the market: picaridin. Both DEET and picaridin are proven to be effective at fending off mosquitoes—and are superior to other repellents when it comes to protection time.
Should you wash DEET off? ›Avoid heavy application or oversaturation. Once you return indoors, make sure you wash off the DEET with soap and water. It's especially important to do this if you plan to reapply the DEET later or the next day.
How long does DEET stay active? ›
DEET—a chemical featured in many popular insect repellent brands—is an effective and highly stable ingredient that, like oil-based products, doesn't expire.
What does DEET stand for? ›What is DEET? DEET (chemical name N,N-diethyl-meta-toluamide) is used as the active ingredient in many insect repellents. Insect repellents that contain DEET offer the best protection against mosquito bites. DEET is designed for direct application to skin to repel insects, rather than kill them.
Does DEET affect the liver? ›While DEET (diethyl-meta-toluamide) is fairly effective at repelling mosquitoes, its toxicity is a major concern for those who have chronic liver disease.
Do you put DEET on skin or clothes? ›A small amount of DEET is absorbed into the body when applied to the skin. This amount may increase when the treated skin is covered with clothing. The body may also absorb increased levels of DEET when alcohol or sunscreen is also applied to the skin.
Which is better picaridin or DEET? ›"Picaridin is a little more effective than DEET and seems to keep mosquitoes at a greater distance," he says. When people use DEET, mosquitoes may land on them but not bite. When they use a product containing picaridin, mosquitoes are less likely to even land.
Does DEET cause neurological problems? ›Recent studies suggest that N, N-diethyl-meta-toluamide (DEET) is an acetylcholinesterase inhibitor and that this action may result in neurotoxicity and pose a risk to humans from its use as an insect repellent.
Is there a natural mosquito repellent? ›Lemon eucalyptus oil
Used since the 1940s, lemon eucalyptus oil is one of the more well-known natural repellents. The Centers for Disease Control and Prevention (CDC) have approved eucalyptus oil as an effective ingredient in mosquito repellent.
The active ingredients in household bug sprays, pyrethroids, are generally considered to be safe in small exposures, Rusyniak said. Exposure to high concentrations could induce respiratory distress and neuroexcitations, leading to sweating, muscle spasms or seizure, and the risk of falling into a coma.
Why is DEET free better? ›Deet-free Mosquito repellants are effective.
In addition to being gentler on the skin, the ingredients found in Deet-Free bug sprays are also less likely to pollute waterways and damage delicate ecosystems.
Not only do mosquitoes bite, causing itchy, red welts, they also persistently buzz around ears at night. To minimize them, sleep far from ponds or stagnant water. It's not advisable to wear DEET-based sprays while you sleep, but essential oils like lavender, geranium, and citronella have deterring properties.
What foods make mosquitoes hate you? ›
- Garlic, onions, and apple cider vinegar, when consumed, are said to change the way you smell and make you less detectable to mosquitoes.
- Tomatoes, beans, and lentils as well as other foods rich in thiamine are said to release a smell that repels mosquitoes and other bugs.
Garlic: The smell of garlic is known to keep pesky mosquitoes at bay. Eating garlic cloves is also known to drive these blood-sucking insects away.
What makes a mosquito bite worse? ›Scratching mosquito bites may make the itching worse. Mosquito bites itch due to inflammation. Rather than relieving the itching, scratching an already inflamed area increases inflammation. This makes the area even itchier.
Why do I get so many mosquito bites on my legs? ›Some mosquito species are leg and ankle biters; they cue into the stinky smell of bacteria on your feet. Other species prefer the head, neck and arms perhaps because of the warmth, smells emitted by your skin, and closeness to carbon dioxide released by your mouth.
What attracts mosquitoes to certain people? ›It's not always a mystery as to why mosquitoes prefer some people over others—it turns out science can offer some clues. Dark clothing, blood type, sweat, carbon dioxide, pregnancy, skin bacteria, and beer consumption are some things researchers have found tend to attract mosquitoes.
Can mosquitoes bite through clothes? ›Unfortunately, mosquitoes can bite through clothes! Mosquitoes are more likely to attack exposed skin but can still pierce through covered areas to reach your hidden blood vessels. While tight-fitting clothing may protect you from ticks, mosquitoes can easily bypass the fabric to bite you.
What color are mosquitoes afraid of? ›To reduce the possibility of a mosquito biting you, you could consider wearing white, green or blue. Lighter colors are less interesting to mosquitos than darker shades like navy and black, red or orange. However, clothing color alone is unlikely to keep mosquitos away for good.
What color clothing repels mosquitoes? ›Certain colors repel mosquitoes. If you don't want to become a mosquito's next meal, try wearing lighter, more subdued hues. White, beige, khaki, pastel yellow, and even soft gray are good options. And as a bonus, these colors will also keep you cooler on a warm day.
Does Pine Sol keep mosquitoes away? ›Fortunately, I have learned two things that keep these critters away and you only need 4 simple items: 2 Spray Bottles, a bottle of Listerine Mint Mouthwash, and bottle of Pine-sol (or eucalyptus oil for a more natural spray). For starters, mosquitoes HATE mint! Pour the Listerine into a spray bottle and spray away!
What lotion do mosquitoes hate? ›3M Ultrathon Insect Repellent Lotion
Another top-selling mosquito repellent lotion is Ultrathon Insect Repellent Lotion from 3M. This lotion contains about 34% DEET to repel not only mosquitoes, but biting flies, chiggers, deer flies, ticks, gnats, and fleas.
What soap do mosquitoes hate? ›
Mosquitoes absolutely hate the smell of lemons or anything remotely citrus-y. The Citronella lemon soap will help ward off mosquitoes and prevent mosquito bites. You'll have to do is use the soap when you're having a bath.
What can I put in my bedroom to keep mosquitoes away? ›Citronella, lemon, cinnamon, and eucalyptus essential oils may deter the pesky bugs, according to a study published in BioMed Research International. The plants produce natural chemicals that interfere with the bugs' sense of smell, which may keep them away from you.
What is the dryer sheet trick? ›The idea is, apparently, dryer sheets absorb static, which also helps them pick up dust. As useful as these sheets are in the laundry and around the house, I couldn't stop thinking about the waste aspect — it's like using a single paper towel once and throwing it away afterward.
Does smoking keep mosquitoes away? ›Like most insects, mosquitoes don't care much for smoke. Having a fire pit burning in your backyard will discourage mosquitoes from hanging around. While it's not a perfect outdoor pest control solution, it does help.
Does coffee grounds keep mosquitoes away? ›Coffee grounds make an effective mosquito repellent because of the strong smell. The coffee grounds will mask the scents on humans that attract mosquitoes - if they can't smell you they can't find you! You can also burn it to create an even stronger aroma - the same way citronella candles keep mosquitoes away.
What kills mosquitoes the best naturally? ›- Burning coffee grounds.
- Lighting lavender candles.
- Leaving plates of sliced lemons or cloves around the house.
- Setting out mosquito traps.
- Spraying with essential oils such as lavender, lemon, or eucalyptus.
"DEET is very safe when used properly," Rodriguez says. For everyday needs, you can use 10% or 20% DEET to avoid mosquito bites. "Higher concentrations of DEET such as DEET 100% are only necessary in places with high mosquito density and risk for mosquito-borne illness," Rodriguez says.
Is 25 percent DEET enough? ›The more DEET a product contains, the longer the repellant can protect against mosquito bites. However, concentrations higher than 50 percent do not increase the length of protection. For most situations, 10 percent to 25 percent DEET is adequate.
Should I use 100% DEET? ›When it comes to a strong chemical such as DEET, it's best to avoid overexposure. So if you want to use DEET, skip the high concentrations. Opt for 7-to-10 percent if you only need a few hours of protection. If you need all-day protection, look for 20-30 percent DEET, ideally in a time-release formulation.
What are the drawbacks of DEET? ›Occasionally, there have been reports of people having negative reactions after excessive use of repellents containing DEET. These effects included seizures, uncoordinated movements, agitation, aggressive behavior, low blood pressure, and skin irritation.
What bug spray has the highest concentration of DEET? ›
Ben's 100% DEET mosquito, tick and insect repellent offers the maximum DEET concentration available. DEET is recommended by the CDC for protection against mosquitos, ticks and biting insects.
Is 25 or 40 DEET better? ›While DEET is effective at small concentrations, higher concentrations offer protection for a longer period of time. For example, about 5 percent DEET protects for about 90 minutes, while about 25 percent DEET may provide about five hours of protection. The highest recommended concentration is 30 percent.
What percentage of DEET do you need to repel ticks? ›25% DEET | EPA registered | 8 hours
The CDC — along with six of our experts — recommends DEET as an effective tick repellent. “The EPA suggests that any product with DEET should have a concentration between 20 and 30 percent of the active ingredient,” says Molaei.
DEET and picaridin are the most effective insect repellent ingredients. Insect repellents with up to 10 per cent DEET or picaridin are suitable for most situations, but use strengths of 15–30 per cent in high-risk areas.
Does DEET wash off with soap? ›Avoid heavy application or oversaturation. Once you return indoors, make sure you wash off the DEET with soap and water. It's especially important to do this if you plan to reapply the DEET later or the next day.
How long does DEET stay effective? ›According to the University of Michigan School of Medicine, a bug spray with 20 percent DEET will protect for about five hours; spray with 7 percent DEET will protect for two or three hours.