Ticks are vile little creatures that can transmit diseases like Lyme, Rocky Mountain Spotted Fever, and Powassan. According to the Center for Disease Control, these diseases are on the rise as ticks expand their geographic rage. “The number of counties in the northeastern and upper midwestern United States that are considered high-risk for Lyme disease increased by more than 300% between 1993 and 2012,“ they write. Lyme, the most prevalent tick-borne disease in America, is potentially debilitating and difficult to diagnose. We believe it is critical to protect yourselves from ticks. As we say in our bug repellent guide, a 20 percent concentration of picaridin repellent works well, but to really give yourself the highest level of protection we recommend using it in conjunction with permethrin-treated clothing.
Permethrin is an insecticide, not a repellent, so it will actually kill ticks and not just send them packing. It’s also different in that it is sprayed on your clothing rather than your skin. Once a piece of clothing is properly treated, the permethrin remains effective for weeks, if not months or years, depending on how it is applied.
What you can do now
You have a few ways to use permethrin. You can buy a spray and treat clothes you already own, buy already treated clothes, or send your clothes to a service for treatment.
Buying a permethrin spray is the easiest way to quickly take action. The most important thing is that the spray has a 0.5 % concentration of permethrin. There are a number of brands available, but we like the Sawyer brand, because of the range of sizes available and the easy spray nozzle.
Some permethrin sprays are made for a yard or for agricultural use. Since those formulas are meant to be sprayed on plants, they won’t stick to your clothes as well, according to Thomas Mather, aka The Tick Guy, director of the University of Rhode Island’s Center for Vector-Borne Disease and the TickEncounter Resource Center. Depending on what brand you end up with, treating clothes yourself means that the permethrin will last anywhere from four to six washings. Even if you don’t wash your treated shoes, Mather recommends re-treating them about once a month.
Sprays are a great everyday fix, but if you’re a dedicated outdoorsperson, looking into pretreated clothes might be worth your time (and remember, they also keep mosquitoes from biting you). If you want to buy pretreated garments, you have a ton of options: Amazon, Insect Shield, L.L.Bean, and REI all sell permethrin-treated clothes; Insect Shield also sells clothes just for kids (and a few things for dogs). These treatments last for about 70 washes.
Insect Shield can also treat clothes you already own. This is the same treatment the company applies to clothes it sells, both under its own brand and others (such as ExOfficio). Insect Shield charges per item of clothing but offers bulk discounts. Getting your treated clothes back takes about two weeks.
Pretreated is the way to go from a cost effectiveness standpoint, Mather told us. “Seventy washes probably gets closer to the life of the clothing for the most part. Four or five doesn't.” And it can be hard to remember to treat clothing yourself every month, he added. Buying it pretreated solves the upkeep problem.
Where to spray it and when
Ticks are less likely to bite if you’re wearing permethrin-treated clothes, and by far the most important thing to treat is what you’re wearing on your feet. Although studies have found that wearing a treated shirt or shorts makes ticks about two to four times less likely to bite, if you treat just your shoes and socks, you’re about 74 times less likely to be bitten by a tick than if you’re wearing untreated footwear, which is a pretty big deal.
“We've done tests with clothing, and we can watch the ticks fall off and die. So there is good scientific evidence that this works and it actually works pretty well,” said Mather. However, you have to be strategic about what treated clothes you wear and when.
For the spring and summer, it’s best to treat your socks and shoes, Mather said. The immature, or nymph-stage, ticks are in the leaf litter at that time of year, and they’re most likely to get on your shoes and crawl up. They’re also so small that they can actually crawl through the weave of your socks, Mather said. “So spray your shoes the first of May, the first of June, first of July, first of August, and that will help you against the ticks that you can't see.”
In the fall, the adult-stage black-legged ticks come out. They tend to crawl up on plants and get on your body higher up, usually around your shins or knees, Mather said. “Then you would like to have treated pants, and you'd like to tuck your shirt tail in so that the ticks stay on the outside of your clothing longer.” If you’re still wearing shorts at that time, make sure to spray them both inside and out if they’re not pretreated.
In the winter, black-legged ticks can still be active as long as they're not frozen on the ground, Mather told us. “These are the first to emerge in the very early spring, followed fairly quickly by the American dog tick adults and the Lone Star tick, both nymph and adults.” So put those permethrin-treated pants back on when the snow melts.
Safety concerns
Some people worry that since permethrin is an insecticide, it will harm them. This is pretty unlikely. It kills ticks by interfering with how neurons fire in bugs’ little brains, causing them to spasm and die. But how our neurons fire is slightly different, plus we’re much larger and can metabolize permethrin before it can get to our nervous system (permethrin is over 2,250 times more toxic to ticks than to humans). Obviously, you shouldn’t eat it, but even if you’re exposed to a lot of permethrin, it’s unlikely to hurt you. According to the TickEncounter Resource Center permethrin fact sheet, a 140-pound person would have no adverse health effects even if exposed to 32 grams of permethrin in a day, and a bottle of clothing treatment has less than 1 gram of permethrin. (If you’re pregnant, know that animal studies have found no evidence that permethrin is harmful. The government gives it a Category B rating since there haven’t been meaningful permethrin studies with pregnant women.)
Permethrin can potentially harm bees, fish, and aquatic invertebrates. And oddly, cats—but only when it’s wet. When the permethrin spray dries, it’s okay for your cat to be around. This goes for fish too—if you step in a stream wearing permethrin-treated shoes, it won’t wash off and hurt the fish, Mather said. “Once it's dried onto the fiber, it doesn't come off very well. That's why it can go through the wash five or 70 times, depending on the mode of application, because it's stuck.”
But will it come off in the laundry and pollute the environment? That’s a much bigger question. Permethrin is a type of molecule known as a pyrethroid. These substances are pretty widely used: They’re in more than 3,500 registered products, including those used on pets and in treated clothing, in mosquito control, and in agriculture, according to the EPA. It’s also the main ingredient in some over-the-counter lice treatments. Permethrin spray for clothing is designed to stick to fiber and comes off only minimally in the wash. Still, research into pyrethroid pollution is ongoing.
Our favorite tick-check method
If you do get a tick, it’s important to remove the insect relatively quickly. Once one crawls onto your body, it can be hours until the tick attaches its horrible sawlike mouth onto you, and then another 12 hours until it starts transmitting disease—except for deer tick disease, which took only 15 minutes in a study on mice (yikes). Remember, black-legged ticks are tiny when they’re nymphs, about the size of a poppy seed (thank you for ruining all poppy seed things forever, CDC), so they can be hard to see.
Because ticks often attach in areas you tend not to pay much attention to—which makes finding them harder—Mather suggests doing tick checks fairly regularly, perhaps during one of life’s most intimate moments. “I noticed that I could see a lot if I just paid attention while I was sitting on the toilet,” Mather said. “I can see down the inside of both of my legs and behind my knees by doing a little twisting. I can push my junk to the left and to the right, and I can kind of check it out to see if I see any ticks there.” He did note that it’s hard to see your own butt, and you might still need help in that area. “But if I do that once or twice a day, I'm doing a pretty reasonable tick check just while I'm multitasking.”
If you do find a tick, don’t panic. First, get some fine-tipped tweezers. Grab the tick as close as you can to your skin, and pull it straight out. Rub the bite with alcohol and wash your hands. Take deep breaths. Eat a poppy seed muffin. Mather said you should try to ID the tick before doing away with it. The TickSpotters program can help identify the type of tick and give you a risk assessment if you send in a clear picture. “If the tick is a risky tick, attached long enough to transmit any germ they might be carrying, then we suggest that people might want to have the tick tested, for peace of mind, and to have more information to pass along to their primary care or veterinary care provider,” Mather said. If you come down with a fever a few weeks later, call your doctor. But remember that if the tick is on you for less than 24 hours, your chances of getting a tick-borne disease are small. And if you remember to wear your summer socks, you have a good chance of killing ticks before they attack.
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