The Myth and Reality of Mosquito Repellents
Tried a “sure-fire” mosquito repellent and still got bitten? It’s not your fault. This post from Inc.com highlights what science says about four supposed mosquito repellents that absolutely don’t work and five that do.
It’s officially summer and you know what that means: hiking, swimming, backyard barbecues…and mosquitoes. Everyone is bothered by them, but some people think they’ve found the perfect antidote to unpleasant and potentially disease-laden mosquito bites. Do these magic cures hold up under scientific testing? In many cases the answer is: Absolutely not.
Believe it or not, mosquitoes are the deadliest creatures to humans on our planet, with more than 1 million deaths a year attributed to the diseases they carry, which include malaria, dengue fever, West Nile virus, Zika, and yellow fever. With climate change causing warmer winters in many places, and thus fewer of the hard frosts that cut down mosquito populations, mosquitoes will only become more numerous in the coming years. White nose syndrome, a fungus that has killed millions of bats in the United States, is worsening the problem, since bats are voracious mosquito eaters.
These are all very good reasons why you need to know the difference between myth and reality when it comes to mosquito control. Here are some mosquito cures people swear by, but science shows do no good whatsoever:
Wouldn’t it be great if you could download an app onto your smartphone that would keep mosquitoes away? It would be, and there are plenty of apps you can download, but don’t expect them to work. These apps (one of which actually claims to be a prank you can use on your friends) are a new version of the small, inexpensive devices that supposedly repelled mosquitoes by emitting the same sound as a flying dragonfly.
Dragonflies are mosquito predators and so, theoretically, the sound of one approaching would cause mosquitoes to flee. In other cases, the sound is supposed to imitate a male mosquito’s mating call. You might not think this would work as a repellent, but consider that only female mosquitoes bite, and only when they have fertilized eggs to lay. Again, according to the theory, female mosquitoes with fertilized eggs don’t want male mosquitoes around them and so will leave the area when they hear one.
The only problem with all this is that when tested, it doesn’t work. Perhaps the sounds really do provide a good imitation of dragonflies or male mosquitoes but there’s no evidence to show that female mosquitoes with fertilized eggs will leave an area where there are mating males. And if you’ve ever sat by the edge of a pond swatting at mosquitoes while watching dragonflies zip around, you know that mosquitoes don’t leave just because a dragonfly is nearby.
2. Avon Skin So Soft
You’ve probably heard that this Avon beauty product through some magical accident of formula also works as a dependable mosquito repellent. It doesn’t, or at least not a very good one. In a 2002 study reported in The New England Journal of Medicine, some exceptionally masochistic test subjects agreed to stick their arms into a cage full of mosquitoes to see how long various repellents would keep them away. Skin So Soft only worked for 10 minutes. A soybean oil-based product called Bite Blocker worked for 94 minutes, so you’re better off with that.
There’s also another Avon alternative. Although Skin So Soft was never intended to be a bug repellent, Avon listened to its customers, as every smart company should, and created a mosquito-repelling version. It’s called Avon Skin So Soft Bug Guard Plus IR3535, and it’s the only product containing IR3535 you can buy in the United States. However, in the NEJM mosquito study, that product only kept mosquitoes away for 23 minutes. So, at least according to that test, you’re still better off with Bite Blocker.
3. Citronella candles
People have been using citronella candles to try to keep mosquitoes away from outdoor gatherings for more than 100 years. Do they work? Not particularly, according to the NEJMstudy. They may draw mosquitoes toward the candle and away from the party but, according to one study noted by WebMD, only because candles emit heat, carbon dioxide, and moisture, all of which attract mosquitoes. Regular candles also emit those things and so should work just as well.
4. Wristbands
Wristbands of any description, whether they emit a sonic tone or carry insect repellent, will–at best–protect your wrist only. The rest of you is still exposed.
So, what does work? The answers are much more boring than smartphone apps or exotic body lotions. Here they are:
1. DEET
The NEJM study concluded that DEET, the active ingredient in most commercial insect repellents, was the most effective mosquito repellent. It’s also an effective repellent against ticks, which can carry some pretty serious diseases themselves.
But wait–isn’t DEET dangerous? Well…it’s unclear. The Environmental Protection Agency and the Center for Disease Control both recommend DEET and say that when used according to directions (in particular, don’t put it under your clothes and don’t let it get in your eyes) there are no ill effects.
On the other hand, exposure to high amounts of the stuff has been shown to kill brain cells in rats. The government says that acceptably low exposure won’t harm you. But no one has ever done a study to determine whether acceptably low levels of the many different toxins all of us are exposed to in daily life can harm us in combination with each other and until someone does, I’m leery of acceptable levels.
That said, there’s no question that things like Zika and West Nile virus can make you very sick or kill you, and some argue that DEET’s effectiveness against mosquitoes makes it a safer bet than risking getting bitten. Your call.
2. Lemon eucalyptus oil
This is the only botanical mosquito repellent recommended by the CDC, and they recommend the oil as formulated in insect repellents such as Repel Lemon Eucalyptus or Off! Botanicals. Pure essential oil made from lemon eucalyptus leaves hasn’t been tested so its effectiveness is unknown.
3. Picaridin
Picaridin has only recently become available in the U.S. and the CDC considers it among the most effective repellents, along with DEET. But is it safe? Testing so far has not turned up the same side effects that DEET has, such as neuro-toxicity. Nay-sayers note that it hasn’t been tested as thoroughly as DEET, at least in this country, which may be true. It’s still likely the better bet between the two. You can find it in Cutter Advanced, and Avon makes a Skin So Soft Bug Guard Plus Picaridin as well.
4. Mosquito traps
Various brands of mosquito traps use a combination of CO² and mosquito bait to attract and then trap mosquitoes. People who use them in mosquito-infested areas find they fill up with dead mosquitoes quickly. No one has done any tests to confirm that this leads to fewer mosquito bites, although logic suggests that it should. However, these devices tend to be pricey, and they won’t eliminate all mosquitoes.
5. Getting rid of standing water
One of the best ways to reduce mosquito infestations is to make sure they have nowhere to lay their eggs. That means eliminating standing water around your home as much as possible–keeping in mind that a thimbleful or less is all they need. Once you empty out an outdoor basin or other container full of standing water, scrub out the inside as well, because mosquito eggs can stick to the sides of the container.
