Stressed? Irritated? Feel like yelling “Fuck you!” to a cruel and aggressive universe? Let me introduce you to my favorite chemical. It’s cheap, it’s effective, and it’s also legal in most states.

Ladies and gentlemen, I give you Permethrin!

I live in a log cabin in the woods and have a four mile hike on a dirt road through trees and fields to my office in town. Until a few years ago my life was complete. Too complete. The damn bugs were driving me crazy. There were mosquitoes, deer flies, black flies, and the threat of ticks outside; and ants and wasps in and around the cabin. I kept local stores in business buying sprays and traps. Then a discussion on another forum[1] induced me to buy a bottle of this:

The idea is that you spray it on clothing, let it dry, and it repels all the buzzing biting stinging nasties. I was desperate. I’d try anything. I tried it.

And it worked, wonderfully.

Permethrin is a potent insecticide that’s safe around animals other than fish, amphibians, and cats. Dogs tick collars are infused with it. When sprayed on a garment and dried, a 0.5% solution of permethrin will actively repel insects for about six weeks and won’t wash out in the laundry. Really.

The reason is that permethrin isn’t water soluble. The Sawyer product above is a solution of permethrin in an oil solvent mixed with water. The permethrin/oil solution *is* water soluble. It’s the same way that water can be dissolved into gasoline using alcohol as an intermediary.

So if the 0.5% solution is sprayed on cloth and the water and solvent evaporated away what remains are tiny crystals of permethrin bound into the threads. Rain and sweat won’t dissolve the crystals and insects are literally repelled. Those that do manage to land on a treated garment will likely die.

I currently have a “bug hat” and a “bug jacket” that I’ve treated and re-treat every few weeks. If I went deep into the woods frequently I’d invest some “bug pants” and “bug socks” for ticks. One of my pleasures is sitting out in an Adirondack chair so I have a “bug towel” that I clip onto it. With the bug hat and bug towel I can sit outside in a pair of shorts and not be bothered by bugs. Before I got the Adirondack chair I saturated a folding camp chair with the same result.

The spray bottle shown above is $16 for 24oz of 0.5% solution. A post on the other forum implied it was possible to mix up your own 0.5% solution so I investigated and found this $46 quart bottle of 36.8% concentrate:

I did some calculations[2] and discovered that that the $16 24oz spray bottle contains about 47 cents of active ingredient. I didn’t buy another spray bottle of pre-mix. I did buy the quart of concentrate, a five gallon carboy with a dispensing cap, a case of chemical-resistant spray bottles, and went into the business of providing free 0.5% solution to all my friends and neighbors.

The concentrate is orange, viscous, and smelly. When dissolved in water it turns milky white. The solution is not stable over the long term. Eventually the permethrin will precipitate and leave white crystals at the bottom of the container. This happens quickly if the solution freezes. Shaking the container will not put the crystals back into solution.

The quart bottle of concentrate came with a thick booklet of instructions and it turns out that the 0.5% solution is more than just an insect repellent; it’s the same stuff that your professional exterminator will spray on your foundation, lawn, and deck. I have a five gallon pump sprayer and the carpenter ants don’t know what hit them. The 0.5% solution is safe on most animals, not cats, and I have some neighbors who spray it on their horses.

Amazon vendors will not ship 36.8% concentrate to all states but each vendor seems to have a different list so it’s worth it to check out all the listings. Lesser concentrations are also available and may not be restricted to licensed professionals.


[1] Is it impolite at this point in our relationship to mention that I frequent other forums?

[2] To make[3] 24oz of 0.5% solution:

0.5% of 24oz is 0.12oz of 100% concentrate

But the quart bottle is 36.8% so 0.33oz of it is required

A quart is 32oz so the quart of concentrate will make 98 24oz batches

$46 / 98 = $0.47

[3] Yes, this is a rough calculation that does not take into account the volume of the concentrate.