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 If you’re planning on spending time outdoors this summer, you’ll find that the insect repellent aisle of your local pharmacy offers a dazzling array of options to protect you from hungry bugs. Hardcore DEET-based sprays like Off! Deep Woods ($6.79 for 6 oz.) promise to ward off ticks, mosquitoes, flies, chiggers, and gnats for an entire day. Other products—such as Avon Skin So Soft Bug Guard Plus ($6.99 for 4 oz.)—contain sunscreen in addition to insect repellent. There are plenty of plant-based potions—Aromaflage ($30 for 8 ml) claims that its proprietary blend of “citrus fruit, warm cedarwood, and silken vanilla” makes for “a sophisticated, uplifting fragrance that also repels insects.” So do any of them get the job done? And do they cause problems for more than just bugs? 
 
 Scientists believe that mosquitoes choose their human victims by the scent of the bacteria on our skin and in our sweat. 
 
 What’s the big deal? I can handle a few mosquito bites. Scientists believe that mosquitoes choose their human victims by the scent of the bacteria on our skin and in our sweat. Because our bacterial communities vary, some of us are more prone to bites than others. To anyone who has scratched herself silly after a camping trip, the importance of an effective repellent is obvious. But even if you’re lucky enough to be unappetizing to mosquitoes, there’s another reason to choose your bug defense carefully: Insect-borne illnesses are on the rise, and some can be serious, even deadly. Lyme disease, which is transmitted by deer ticks, causes debilitating symptoms in more than 20,000 people every year. In 2013, 2,374 people in 48 states contracted the mosquito-borne disease West Nile virus, and 114 of them died. As climate change intensifies, public health experts expect that more breeds of mosquito will thrive in the United States. As a result, they predict an uptick in West Nile and other insect-borne illnesses, such as yellow fever. Since 2001, Florida, Hawaii, and Texas have had outbreaks of dengue, another mosquito-borne disease that had been considered eliminated in the United States since 1945. 
 
 What should I look for in a repellent? Good question. Despite massive industry lobbying, sunscreen manufacturers must now state clearly on the packaging how well and how long a product works. Repellent companies, however, are hardly required to follow any rules at all. In 2013, when the health watchdog Environmental Working Group analyzed various repellents, researchers found that manufacturers’ claims about how long products last varied widely—even with the same active ingredient in the same concentrations. Some manufacturers claimed that their products were waterproof, even though—beachgoers beware—they did not offer proof. Others boasted exotic active ingredients—like clove oil and lemongrass oil—that have not been adequately tested and may contain high concentrations of allergens. “There should be a way for consumers to compare products,” says EWG senior scientist David Andrews. “And right now, there is really not.” 
 
 Doesn’t the government have some basic rules about what they can put on the labels? Not really. Last year, the Environmental Protection Agency drafted a label template that tells consumers what kinds of insects a product protects against and how often it needs to be reapplied. But it’s completely voluntary. What’s more, the graphic will only apply to repellents that you apply to your skin, not wristbands, patches, candles, sonic devices, or any other products that claim to deter bugs. 
 
 So do those wristbands work? Not as well as skin-applied repellents. In 2011, Australian medical entomologist Cameron Webb tested mosquito repellent wristbands and found them much less effective than skin-applied products containing DEET; they only offered protection in a very small area around the wrist. “There is no product—candles, fans, coils, patches, or anything else—that I am aware of that provides comparable protection to a DEET skin-based repellent,” he says. “Even if they work a little bit, they’re not going to protect all of your exposed skin.” Spatial products such as candles, coils, and smoke do drive away bugs, though the Centers for Disease Control and Prevention notes that they “have not yet been adequately evaluated in peer-reviewed studies for their efficacy in preventing vectorborne disease.” 
 
 Studies have found virtually no health risks associated with DEET at the concentrations found in commercial repellents. 
 
 Wait, isn’t DEET toxic? No. In the ’80s, there were reports of children having seizures after using DEET-based products, but the exact cause of the seizures was never determined. Subsequent studies have found virtually no health risks associated with the ingredient at the concentrations found in commercial repellents. 
 
 Anything else I should steer clear of? EWG suggests skipping products with plant-based active ingredients, even though they sound greener; the EPA does not require registration of these substances, and no one knows how safe or effective they are. The CDC recommends avoiding combined sunscreen-repellents because sunscreen requires much more frequent application than repellent—and the effect of overapplication of repellent hasn’t been well studied. And don’t trust label claims about how long a product can last. That’s determined by the percentage of its active ingredients—but without any way to compare, consumers are left to trial and error. 
 
 So what does work? For the best protection against both mosquitoes and ticks, the CDC recommends products containing DEET. For just mosquitoes, the agency also approves of products with the active ingredients picaridin (the active ingredient in most Avon Skin So Soft products), IR3535, and oil of lemon eucalyptus—which, despite its natural-sounding name, is actually a synthetic formulation. EWG found all three of these ingredients to be just as effective as DEET. “You don’t really want to mess around with a product that might or might not work,” says Webb, the Australian entomologist. “Where insect-borne diseases are concerned, it only takes one bite.” And as for the sheer itchy misery of being a mosquito’s idea of a five-star restaurant? Well, you probably don’t want to mess around with that, either. 

 Why mosquitoes bite some people and not others Science explains one of life's great mysteries. Plus! A natural remedy to keep you insect-free all summer 
 
 Why are some people so much more attractive to mosquitoes than others? And what can you do about the pesky little bloodsuckers, especially if you don’t want to resort to DEET? (DEET, while effective, is also weakly neurotoxic in humans.) 
 
 To start, there are some 150 different species of mosquitoes in the United States, and they differ in biting persistence, habits, ability to transmit disease, and even flying ability. 
 
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 Mosquitoes of the genus Culex are painful and persistent biters and they will gladly fly into your house to bite you. They bite at dusk and after dark, and they can spread West Nile virus. On the upside, however, they are not strong fliers and won’t fly long distances from where they hatched. And, they’d prefer to bite a bird than a human. A common Culex species in the U.S. is C. pipiens, the Northern House mosquito. 
 
 Then there’s the genus Aedes, which includes A. aegyptiand A. albopictus, the Asian Tiger mosquito. The former is not a problem in the U.S.; the latter is. Both can transmit Yellow Fever and Dengue Fever. Aedes mosquitoes feed early in the morning as well as at dusk and into the evening. They might also bite you during the day if it’s cloudy or if you wander into a shady place. Fortunately, they probably won’t enter your house – but they do prefer biting mammals like humans over other animals, and they are very strong fliers. 
 
 One other notable genus of mosquitoes areAnopheles mosquitoes. They are the ones responsible for transmitting malaria. In the U.S., that mostly means A. quadrimaculatus, which lives in the central and eastern U.S., as far north as southern Canada. 
 
 But if we have Anopheles mosquitoes, then why don’t we have malaria? The answer, in part, is due to climate. According to Andrew Githeko, a Kenyan scientist who studies malaria, malaria only occurs in places where the average temperature is above 18C (64.4F). Below that, the mosquito dies before the parasite matures, and this prevents transmission. In Kenya, he discovered malaria already moving into new areas as the climate warmed. Fortunately, malaria is not endemic to the U.S. as it is in Kenya. And if the U.S. lacks a base of humans and mosquitoes carrying the parasite, then that prevents the spread of the disease. 
 
 These different genera and species not only differ in the ways listed above; they also differ slightly in what attracts them to hosts they wish to bite. Mosquitoes use carbon dioxide, heat, moisture, scent, and even vision to locate hosts. When they are sniffing us out, they hone in on a large number of chemicals. A 2000 study identified 346 chemicals from human hand odors, of which 277 were potential mosquito attractants. 
 
 The most significant chemicals mosquitoes use to locate us and bite us include l-lactic acid, ammonia, carboxylic acids, and octenol, in combination with one another. In experiments, scientists found that adding l-lactic acid to the scent of an unattractive person made them more attractive to Aedes aegypti mosquitoes, and vice versa. Additionally, the presence of carbon dioxide makes A. aegyptimosquitoes more sensitive to human skin odors. 
 
 A 1999 study found that malarial mosquitoes were not attracted to fresh human sweat, but found attractive after it was incubated for one or two days. During the two days, bacteria in the sweat multiplied and the pH changed from acidic to alkaline, signifying a decomposition of sweat components into ammonia. The study also notes that malarial mosquitoes flock to the scent of limburger cheese, which resembles human foot odor. Githeko confirms that, indeed, malarial mosquitoes are attracted to chemicals produced by bacteria on one’s feet, and they will even bite a pair of smelly socks if you hang them up after wearing them for a few days. 
 
 Unfortunately, the keep-your-feet-clean-to-avoid-mosquito bites trick only works for malarial mosquitoes, since other species are not especially attracted by foot odor. That makes this useful information for staying healthy while traveling in the tropics, but less useful if you just want to avoid itching in the United States. 
 
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 Still, the identification of skin bacteria as playing a role in one’s attractiveness to mosquitoes provides a clue. Among the aforementioned carboxylic acids that alert mosquitoes to our presence are several short-chain and medium-chain fatty acids that are associated with body odor. Sweat itself is odorless until bacteria act on it to make it stink. Bacteria, by metabolizing our sweat, are essentially sending up a red flag to tell mosquitoes we’re here. 
 
 Yet another component of human odor is genetic. Although some theorize that individuals mosquitoes find unattractive simply produce less in the way of attractants, an alternative theory asserts that they produce components that interfere with mosquitoes’ ability to find their hosts. In fact, a 2008 study identified five such chemicals produced by humans found unattractive to mosquitoes. 
 
 To those of us who are genetically doomed to be mosquito bait, this information provides limited help. Perhaps we can bathe around dusk when the mosquitoes come out to get the day’s sweat and its associated odors off of us, or rub ourselves down with antimicrobial plants like sage to curb the actions of our skin microbiota, but most likely we just need a good repellent. Or one of those full-body mosquito net suits. 
 
 For those looking to avoid toxic chemicals like DEET or permethrin (a possibly carcinogenic insecticide frequently used to treat clothing and mosquito nets), plants might hold the key to repelling mosquitoes. One of the most often cited is lemon eucalyptus. In fact, a 2014 Australianstudy found that a mixture of 32 percent lemon eucalyptus oil provided more than 95 percent protection from mosquitoes for three hours, compared to a 40 percent DEET repellent that gave test subjects 100 percent protection for seven hours. 
 
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 But lemon eucalyptus is not the only option. A 2013 study examined the ability of 20 different plant essential oils to repel malarial mosquitoes. Notably, rosemary, lemon, eucalyptus, neem, and pennyroyal each had no repellent effect. The three best were cinnamon, citronella, and thyme, which were repellent, irritating, and toxic to the mosquitoes. Additionally, they found that cumin, lemongrass, coleus, and thyme were irritants to the mosquitoes at all concentrations. Another 2013 study found that cinnamon repelled the Asian Tiger mosquito, and so did a plant called Herba Schizonapetae that is used in Chinese medicine. Yet another plant that proved effective in studies is Nepeta parnassicus, a species in the mint family related to catnip. 
 
 Unfortunately, plant based products evaporate quickly, which means they must be re-applied. But another study, published in 2001, tried the novel step of adding vanillin to the essential oils it tested on several species of mosquitoes. Vanillin, the primary component of vanilla (which is sometimes created synthetically and used as cheap vanilla flavor), extended the efficacy of the four plants tested (turmeric, kaffir lime, citronella and hairy basil). One commercial product that makes use of this finding is Dr. Mercola’s Bug Spray, which combines citronella, lemongrass, peppermint, and vanillin. 
 
 Or, if none of the above works, use jewelweed after you get bitten. If you live in the eastern half of the United States, you are in luck, because this beautiful wildflower literally grows as a weed. Grab a few leaves, mush them up in your fingers until they are mucilaginous, and apply them to your bites. Voila! The itch is gone.
– At your next barbecue, your friend may be slapping mosquitoes left and right, while they just aren't that into you. Don't be insulted: It may have to do with the chemicals in your skin, Jill Richardson explains at Salon. There are 346 chemicals involved in the scent of human hands, a study found in 2000, and 277 of them can attract the annoying critters. A key one seems to be l-lactic acid, which, when added to the scent of a less-targeted person, can make certain mosquitoes go after them. It's also been suggested that some people are lucky enough to carry chemicals that actually get in the way when mosquitoes are looking for lunch. And when it comes to malarial mosquitoes—not a big problem in the US—the bacteria in foot odor is tempting. They'll even go after limburger cheese, which smells like feet, Richardson notes. As for how to deal with them, there's controversy over the use of bug repellent DEET, which Salon calls mildly neurotoxic. But Mother Jones notes that the cause of supposedly DEET-linked seizures in children in the 1980s remains unclear, and newer studies have shown little in the way of health risks from small amounts of the stuff. Still, if you want to avoid it, a recent study suggested lemon eucalyptus oil could do the trick against mosquitoes.