Permethrin is a highly effective insecticide that is widely used to protect against insects. It is most commonly used before a backpacking trip or thru-hike on gear and clothing as a deterrent to both ticks and mosquitos (and a whole lot more). It is one of the most effective ways to limit interactions with annoying insects and improve your time on an adventure in the wilderness. But what is permethrin, and how does permethrin work?

Permethrin – The Pre Treatment
Protection from: Ticks, mosquitoes, spiders, chiggers, mites, and more than 55 other kinds of insects
Permethrin is an insecticide originally coming from the chrysanthemum flower. It repels mites, ticks, mosquitos, spiders, chiggers, and a number of other insects and can kill them if they ingest it. Even in the heaviest tick environments, permethrin made a big difference in the number of ticks that I saw on my clothing.
What is Permethrin, and how does Permethrin work?
Permethrin is a synthetic insecticide that can be used to treat clothing and gear against mosquitoes and ticks. When permethrin is applied to clothing, it bonds to the fabric fibers and creates a barrier that repels and kills insects on contact. The insecticide attacks insects’ nervous system, causing paralysis and, ultimately death.
Permethrin-treated clothing can provide long-lasting protection against insects, even after multiple washings. The insecticide can remain effective for up to six weeks, depending on the level of exposure to sunlight and washing. Permethrin-treated clothing is especially effective at repelling ticks, which, believe it or not, are present in all 50 states.
How to use permethrin
Choose the clothing and gear that you want to treat. Permethrin can be used on a variety of fabrics, including synthetic and natural fibers.
Make sure the clothing and gear is clean and dry before applying Permethrin. Washing the clothing and gear with detergent and no fabric softener is recommended.
Apply Permethrin to the clothing and gear outdoors in a well-ventilated area. Place the item on a flat surface and spray the product evenly over the entire surface until it is damp, but not soaked.
Allow the treated clothing and gear to dry completely before wearing or packing. This may take several hours, depending on the weather conditions.
Once dry, the permethrin-treated clothing and gear is ready to wear or pack for your outdoor activities. Be sure to avoid direct skin contact with the permethrin-treated fabric, especially when wet.
Permethrin can also be applied to gear such as tents, sleeping bags, and backpacks. Spray the product on the outside of the gear and allow it to dry completely before use.
Permethrin-treated clothing and gear can be washed up to six times or six weeks, whichever comes first, before a reapplication is necessary.
Other options
Chemical repellents are the most common for repelling mosquitoes and ticks. The active ingredients are usually DEET, picaridin, or permethrin. DEET and picaridin are skin-applied repellents, while permethrin (above) is a treatment for clothing and gear. DEET and picaridin are effective at repelling mosquitoes and ticks for several hours, while permethrin-treated clothing can provide long-lasting protection against ticks.
Natural remedies such as essential oils, garlic, and herbal sprays are another option for protecting against mosquitoes and ticks.
Physical barriers like mosquito nets and tick-proof clothing still remain the best overall, but now you have a few more tools in your toolkit.
Other Mosquito and Tick strategies
Treated Clothing – For wearing during the backpacking trip
Picaridin – A repellent for applying during a backpacking trip
Deet – A repellent for applying during a backpacking trip
Head Net – For wearing during a backpacking trip
Where are mosquitos the worst on the Pacific Crest Trail?
The worst mosquitos on the PCT tend to start in the Sierra Nevada Mountains. From there, they continue to be a pest until the Washington border. But, as the summer goes on, there should be noticeably less of the pests, especially in August and September.

Insect Repellent Chart Courtesy of REI