With summer in full swing and mosquitoes flitting about you, you may have heard that citronella—an herbal oil found in lemongrass—can banish bugs naturally without the need to resort to toxic pesticides such as DEET. But are citronella candles really effective? We asked the insect experts to give us a straight answer on just how citronella works—and when it doesn’t—as well as other natural mosquito repellents on the market.
How citronella candles work
To begin with, it helps to understand what citronella candles are supposed to do. Contrary to popular opinion, the scent isn’t toxic or irritating to mosquitoes.
“The mechanism by which citronella repels mosquitoes involves it masking human odors so that mosquitoes don’t detect the presence of a potential host,” says Joseph M. Conlon, technical adviser at the American Mosquito Control Association.
In plain English: These little bugs find you by your scent, more or less. They pick up on chemicals and odors on your skin, and the carbon dioxide you exhale as you breathe. Citronella is supposed to block all those olfactory signals from mosquitoes.
At least, that’s how citronella candles are supposed to work. The catch? Conditions have to be just right for that to happen.
Candles and other “spatial repellents” (as opposed to repellents you apply directly to your skin) sometimes fail to do their job because they’re outdoor products. And in the outdoors you have wind, rain, and humidity—all elements that dilute the product, which compromises its repellency, says Conlon.
In other words, if it’s windy, that citronella candle isn’t going to work, since the scented cloud cloaking your whereabouts will be whisked away in the breeze.
Do ultrasonic mosquito repellents work?
How about those ultrasonic mosquito repellents, which supposedly emit a frequency these insects can’t stand?
Sadly, studies have consistently shown them to have no effect on how attracted mosquitoes are to their food source. In fact, in one study, sonic and ultrasonic devices correlated to more mosquito bites, so that’s kind of counterproductive.
Do mosquito repellent wristbands work?
What about those mosquito repellent wristbands?
Results are mixed. One study published in the Journal of Insect Science showed that most scented bracelet repellents are also ineffective; however, one wearable device tested by this study’s researchers that worked is the OFF! Clip-On metofluthrin nebulizer. This bracelet emits a vapor of metofluthrin, a neurotoxin that repels and even kills mosquitoes. This is a serious insecticide, but at least you don’t have to apply it directly to your skin.
If you prefer a repellent wristband that uses more natural ingredients, a USDA study found Terminix AllClear Sidekick mosquito repeller was effective. Terminix uses a mix of cinnamon, geranium, peppermint, lemongrass, and eugenol oils.
But again, conditions have to be perfect. With all wristbands, as with candles, “repellency is only obtained in areas of little or no wind movement,” says Conlon. “Breezes will waft the repellent away from the body, reducing its concentration and compromising how well it works.”
Do natural mosquito repellents work?
Spend some time Googling “natural mosquito repellents” and seemingly every essential oil and even a few vegetables will show up. But be skeptical.
Ingredients such as absinthe, anise, bergamot, certain varieties of cedar and cypress, blue eucalyptus, ginger, garlic, and geranium don’t do much at all in tests, Conlon says. Others—such as betel pepper, clove, coconut oil, red eucalyptus, lily of the valley, neem, patchouli, and pennyroyal—either have toxicity issues or are too expensive or difficult to formulate into an effective repellent.
While experimenting with DIY herbal bug sprays seems like a safe and gentle approach, unless you’re a skilled chemist, you could do more damage than good.
So is it back to dousing yourself in DEET? Not necessarily.
Conlon says oil of lemon-eucalyptus, sold as Repel(R), is effective against mosquitoes and ticks. However, the EPA warns against using it on children under the age of 3. Products with 7% refined oil of Nepeta cataria (also known as catnip) can provide seven hours of repellency. Keep in mind, this is a specially formulated version of the herb’s oil. Rubbing catnip oil or leaves directly on your skin can lead to irritation.
The EPA has an online tool to help you find the right insect repellent for you.
