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My Long Trail Black Fly Defense Strategy

Black flies are prevalent on the Long Trail in Vermont from spring through mid-summer. I’m going to be backpacking then and I’ve been devising some strategies to reduce the annoyance and health risk they pose.

My first line of defense is gong to be clothing. Although I hate hiking in long pants, I’m going to wear the bottom halves of my convertible pants as well as gaiters to keep the bugs from flying up my legs. I’m also going to find a highly breathable, lightweight long sleeve shirt. Average summer time temps on the Long Trail are in the low 70’s, so hopefully this will be tolerable except under periods of high exertion.

Buzz Off Ex officio Hat

Next comes the hat system. Unfortunately, I can’t wear a head/bug net. Whenever I put a fine mesh net over my head, I get incredibly noxious and want to puke. I think it has something to do with being near-sighted. So, plan B is to wear a lightweight nylon billed hat with an optional skirt add-on to protect the back of my neck. I’m also going to try wearing a very lightweight balaclava for maximum coverage around the sides of the face and front of the neck.

My second line of defense is Permethrin. This is active ingredient on Buzz Off Clothing from Ex Officio. Ex Officio has recently replaced the Buzz Off brand name with the Insect Shield line of outdoor clothing.

Permethrin is a synthetic analog of a naturally occurring insecticide derived from chrysanthemum flowers. When applied to clothing it chemically bonds to clothing fibers as it dries remaining effective through multiple washings. It is not effective or toxic when applied to your skin, but kills black flies, mosquitos and ticks on contact when they land on treated clothing. It kills bugs by overstimulating their nervous systems. I guess they just freak out and die.

I’ve soaked clothing clothing in Permethrin, in the past, before going a safari trip to Tanzania, where the black flies are the size of bumble bees and make a chitenous crunch when you smash them against a Land Rover window. It worked really well then. I already have a Buzz Off hat and convertible hiking pants, so I will be soaking my shirt, balaclava, socks, and lightweight gloves in Permethrin.

My third line of defense is my Ben’s DEET. I love this stuff because it comes in a tiny 1.25 oz pump bottle that is lightweight and helps you accurately target the spray where it is needed without waste. I use the 100% strength as well as the 30% strength. The 30% strength will retain its efficacy for about 5 hours on your skin, according to the FDA. The 100% strength retains it’s efficacy for 10-13 hours depending on insect type.


  1. It has been a couple of years now, do you still feel the same way about that hat??

  2. I still have it – but it doesn't get used much. The bugs weren't that bad. I'm going to keep it for a desert trek.

  3. I've read with interest your posts about Black Fly protection along the Long Trail. You indicated that your "…going to find a highly breathable, lightweight long sleeve shirt" and treat it with permethrin. I'd be interested in knowing the specifics of what worked for you, and if you've since revised your 2008 LT bug strategy.
    Thank you

  4. I got rid of the stupid hat, but the long shirt, long pants, and permethrin worked fine. I think I got one or two bites the entire trip. I barely used any DEET, and think the whole Black Fly mania in Vermont is a bit over-rated.

  5. In your opinion, would a lightweight breathable Techwick type long shirt treated with permethrin be suitable? Alone my 3.5oz wind shirt is bug proof, but often I find it too 'hot' to hike in. I'm looking for a more breathable solution.

  6. A wind shirt will be way to warm. I've treated my techwick shirts with permethrin and they didn't dissolve.

  7. Campmor has been selling a "Net" set, top and bottom that I've used on the PCT during the height of the Sierra bug hatch and have used here in the South during the Tallendega bug hatch and have had wonderful success with it. I have sprayed both Deet & Permethrin on it and have noticed litle difference in the two other than ordor..Easily washed at home on the gentle cycle and air dried….

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