In order to ward off mosquitoes, my mother used to dust us kids with sulfur powder before we headed out to play. Growing up, I visited a farmer who had a monster bug zapper, glowing purple-blue, which he swore kept mosquitoes and all sorts of other flying insects to a minimum. And in college, I was charmed when a friend put citronella candles in tiny buckets on her patio to keep the little biters away.
But the sorry fact is that none of these work. Mosquitoes don’t care what you’ve been eating: garlic, sugar, onions, or Vitamin B. And citronella, whether it be in the form of spray or candles or oil you dab on your wrist or the plant proper, doesn’t faze them much.
As long as there have been mosquitoes and humans coexisting on this planet, we’ve been looking for ways to make the pesky pests leave us alone. Our inventive human brains have come up with all kinds of lotions and sprays to repel them. Which ones really work?
The truth about DEET
When it comes to keeping mosquitoes at bay, the stakes are higher than they used to be. These days, what’s at issue isn’t just some itchy bumps. In some regions of the country, mosquito-carried West Nile virus is a concern, as is Lyme disease, which is carried by ticks. And a good insect repellent will repel not only mosquitoes but also ticks and a variety of other biting insects.
According to Wayne Rowley, professor emeritus of entomology and an internationally recognised mosquito expert, DEET is still the gold standard in mosquito repellents. (DEET is a rough abbreviation of its chemical makeup of N, N-diethyl-m-touluamide.) Study after study has shown that it’s by far the most effective repellent—and despite its reputation, DEET has demonstrated no ill effects when used as recommended. Further, DEET-based products reliably repel a wide variety of biting insects, while others may or may not repel ticks.
Several years ago, the Environmental Protection Agency issued some precautions about DEET repellents because of reported effects on children. But subsequent studies have found no correlation. Most current recommendation states that repellents containing DEET are the most effective against mosquitoes and other disease-carrying insects. It concludes that the benefits of DEET reach a peak at the 30 percent concentration range, which is the maximum concentration recommended for infants and children. It further recommends that DEET not be used on children under 2 months.
One thing that may give DEET a bad rep is its unpleasant smell and stinging sensation, especially if any spray drifts into eyes or mouths (which you’re not supposed to do, but if you’ve ever tried to spray repellent on a squirming child, you’ll understand how problematic following label directions can be). If the smell and sting bother you, look for a low-odour formulation or one with a lower concentration of DEET, such as those made for children. Also look for repellents that boast they have a “clean feel” or similar wording. There’s usually a tradeoff in protection time with these formulations, but if you’re just going outside for a little early-morning watering, it might be exactly what you need.
DEET-based repellents, like most repellents, also have an oily feel. This helps prevent your skin from emitting the chemicals mosquitoes so love, but it also makes you want to take a shower the moment you come inside.
Despite DEET’s advantages, many people would rather use a repellent with fewer chemicals when practical. That’s why the development of a new insect repellent called Picaridin has been welcome. It has been registered with the EPA, which indicates it’s been reviewed for efficacy and safety when used as directed on its label. Its manufacturers say it’s more pleasant than DEET to use and has a light, clean feel.
Repellents containing oil of lemon eucalyptus have also been cleared by the EPA as having a high level of effectiveness and safety, though these repellents don’t offer as much protection time as those with the highest levels of DEET.
There are a lot of other formulations out there that claim to repel mosquitoes and other biting insects. Some don’t work even for a second. And some, such as Skin-So-Soft bath oil, have been shown to work—but only for 10 minutes. Buzz Away, which is 5 percent citronella, has been shown to work for 14 minutes.
Why these work at all is a mystery, says Rowley. Scientists still don’t understand why DEET works, and it’s been in use for nearly half a century.
But rest assured that scientists will continue to search for ways to repel mosquitoes in ever more inventive, effective, and safe ways. It’s a battle that will continue to be waged until either humans or mosquitoes stop inhabiting this earth.
• Stay away from mosquito-heavy areas at dawn and dusk, the insects’ most active time.
• Mosquitoes can bite through tight clothing, such as jeans. Opt for loose, light clothing. The natural movement of the fabric makes it tough for mosquitoes to take a nip.
• When using insect repellents, cover every inch of skin. If you miss just a patch, insects will bite you there.
• If you’re sweating a lot or getting wet, the repellent may wash off and become less effective sooner. Also, the Centers for Disease Control doesn’t recommend combination sunblocks/insect repellents. The dilution with the sunblock reduces the repellent’s effectiveness. Plus, most sunblocks need to be applied more frequently than insect repellents do, so you’re applying more repellent chemicals than you need.
• Follow label directions exactly.
• Don’t let children apply insect repellents themselves. It’s too easy for them to do a slap-dash job and miss spots.
• Mosquitoes don’t like wind. Hang out where there’s a breeze, or turn on your porch’s ceiling fan.
• Mosquitoes hone in on people in part based on how much carbon dioxide they’re giving off. That’s why they’re attracted to large groups of people and those who are breathing harder when gardening or exercising. They’re also drawn to people who are sweating, women in the first half of their cycles, and pregnant women.