Will bug-repellent clothing protect you from being bitten?

Last summer, a colleague tried out a bug-repellent shirt on a five-day hike in the Cascade Mountain Range. While hiking , she didn’t notice bugs. But at the swampy lakes at the top, there were plenty. She was worried about mosquitoes and ticks — and was bitten by both. Now, she’s skeptical of the shirt’s effectiveness in severe conditions. “I’ll wear it again in a mild bug situation,” she says.

Her experience highlights a common issue with insect-repellent clothing: It’s more effective in certain circumstances and when used properly. “A lot of people do it the wrong way,” says Thomas Mather, director at the University of Rhode Island’s Center for Vector-Borne Disease and the TickEncounter Resource Center. “So they’re doing something, but they’re not getting the same level of protection” they would if the products were used correctly.

Disease cases from mosquito, tick, and flea bites more than tripled nationally from 2004 to 2016, according to the Centers for Disease Control and Prevention . New England, a hotbed for tick-caused Lyme disease, had 8,000 reported cases in 2017, and just over 500 cases of mosquito-borne diseases reported in 2016. “There are ticks in more places . . . than ever before,” Mather says, “and that puts more and more people at risk.”

One way to ward off mosquitoes and ticks, according to the CDC, is by wearing clothing treated with permethrin, a synthetic chemical and insecticide. The EPA classifies permethrin as a likely human carcinogen if eaten but says its evaluation of factory-treated clothing for cancer risk “resulted in risk estimates below our level of concern.”

Permethrin-treated clothing works well against ticks, Mather says. A 2011 URI study found that people wearing treated shoes, socks, shorts, and T-shirts had 3.4 times fewer bites than those who didn’t.

You can buy pretreated items including pants, hoodies, and socks from retailers such as L.L. Bean and ExOfficio, and directly from technology provider Insect Shield, which says its products fend off mosquitos, ticks, and other insects for up to 70 washes.

You can also send clothes to Insect Shield for treatment. Or spray permethrin labeled for clothing yourself; Sawyer’s 12-ounce spray coats four garments and lasts up to six washes or six weeks.

Here’s how to avoid mistakes — and bugs:

1. Protect exposed skin

Even if you don bug-busting garb, “It’s not a force field,” says Jeff Miller, outdoor equipment merchant at L.L. Bean in Freeport, Maine. You still need to apply bug repellent on bare skin.

2. Don’t ignore your feet and legs

To ward off ticks, Mather says the priority should be wearing treated shoes and socks, then pants or shorts. Immature ticks, which are active from May to August, typically start on the ground and crawl up. In the fall, when active adult ticks tend to land on shins and knees, transition to treated pants and tuck your shirt in.

For mosquitoes, Joseph Conlon, technical adviser at the New Jersey-based American Mosquito Control Association, suggests covering up with pants and long-sleeved shirts, especially around sunrise and sunset when mosquitos are very active.

3. Use permethrin repellents properly

If you’re going the DIY route, the National Pesticide Information Center advises using only permethrin products made for clothing. Don’t apply other tick repellents to clothing, and stay away from permethrin formulations designed for agriculture.

4. Spray enough

A few light spritzes on the way to the park won’t cut it. When pretreating , spray the fabric while you aren’t wearing it and let it dry. “Mostly ticks are going to crawl up the insides of your clothing,” Mather says. But don’t overspray, Conlon advises. Also, treat and dry the clothes outdoors.

The chemical is harmful to cats (not dogs), so they shouldn’t be exposed to sprayed clothing until it’s dry. It’s also highly toxic to aquatic creatures as well as bees and other beneficial insects, so keep it out of storm drains, ditches, gutters, or surface waters, Sawyer cautions. Don’t dump water used to wash treating equipment into lakes or other bodies of water, or spray the chemical near aquariums and flowers.

5. Don’t apply to your skin

Permethrin treatments are intended for clothing only and shouldn’t be applied to the skin, the CDC says.

6. Read labels

Permethrin is an insecticide, and it’s important to follow instructions for treated clothing and sprays. They carry labels with directions and precautions for safe use and optimal protection. When purchasing treated clothes, look for EPA registrations on hang-tags.