You’re enjoying a strenuous day hike in Congaree National Park in South Carolina after a recent rain. Sweating, you become aware of a buzzing sound; it’s faint at first, and then it’s louder. No, it’s not your phone. It’s a vast swarm of hungry mosquitoes, and they’re out for blood. Your blood. What should you do?
Swatting at them is one option … and nothing beats the satisfying thwack of a smashed bloodsucker. That said, in this situation, an ounce of prevention is worth a pint of blood. And there are also steps to reduce the itch after the bite.
Vast reams of research exist on what — and who — attracts mosquitoes. The insects appear to be universally attracted to the carbon dioxide people and other animals exhale, the reason backyard mosquito traps use CO2 canisters to lure them in.
Short of holding your breath, this is an attractant you’re not going to be able to avoid. But the pests are also attracted to scents and chemicals humans and animals emit — and with thousands of species of mosquitoes and billions of people worldwide, experts have not been able to isolate them all.
According to the Centers for Disease Control and Prevention, perhaps one in 10 people are considered “highly attractive” to some mosquito species, and these lucky few will be targeted over competing sources of blood. Uric acid, cholesterol and steroid compounds when present in sweat on the skin have also been known to draw mosquitoes.
The easiest (and, let’s be honest here, least-likely-to-be-used-in-hot-weather) method of defeating mosquitoes is to cover the skin: long pants, long-sleeved shirt, long socks and even a head net. However, mosquitoes can easily bite through some fabrics (especially knits and stockings), so tight-weave materials are most effective. Clothes can also be treated with permethrin, a chemical deterrent used on mosquito netting. There is some evidence mosquitoes are attracted to dark-colored clothing, as well, so dress accordingly.
Mosquito repellents that contain DEET, Picaridin, Bayrepel, oil of lemon eucalyptus (more on this below) and Para-menthane-diol (or PMD, which is the compound in the oil) have been clinically shown to repel mosquitoes and are available in various brands of over-the-counter sprays and creams. The higher the concentration of chemical repellent, the more effective and longer lasting the product is likely to be.
There are numerous brands of “natural” or “homeopathic” insect repellents available. Consumer Reports tested many of them and found their efficacy to be, overall, highly questionable. Only one naturally occurring compound — the aforementioned oil of lemon eucalyptus — was recommended.
Are these chemicals safe to use? When used as directed, the CDC says yes. With that said, chemical-based repellents are just that — chemicals — and should not be ingested or sprayed near a person’s eyes. Consumer Reports found that products with higher chemical concentrations (more than 30 percent) might also cause disorientation in some people, so take care when using any of these repellents. They should be reapplied after swimming or excessive sweating.
What if you have no repellent? Use air. Mosquitoes are weak flyers: Even a moderate breeze might keep them off you, at least temporarily. So consider a handheld or electric fan to disturb the air around you. Another tactic is simply to slow down. Elevated heart rate = heavier breathing = more carbon dioxide = more mosquitoes. Another tactic, while not foolproof, has to do with timing. Dawn and dusk are typically the least windy times of day, which is when many (though not all) mosquito species tend to feed. Avoiding hiking at these times might offer some benefit.
If you are bitten, don’t scratch: Scratching can lead to inflammation and infection. Instead, try some ice on the bite. (I prefer using the tried-and-true fingernail-carved “X” on the bump, though I can’t prove its clinical success rate.)
What about Zika? While it is a concern, the Zika virus has not been found in mosquitoes in the vast majority of U.S. states; West Nile is much more widespread. However, if you or a partner are planning to visit an area where Zika is a concern, you should follow the CDC guidelines regarding travel and bite-prevention measures. Read more at cdc.gov/zika
There is one safe, completely foolproof way to avoid mosquito bites: Attract only the males, since they don’t bite. If you figure out how to do that, please let me know.
FIND MORE info on mosquito-borne illnesses in the BSA’s health and safety reminder.