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Testing Mark’s permethrin-treated clothing

Testing Mark's permethrin-treated clothing

Brian Patton takes notes while measuring a mosquito-infested trail on the west slope of the Canadian Rockies. Bug-protection includes the permethrin-treated WindRiver No Fly Zone ball cap, shirt and pants. Rhonda Allen photo.

When Mark’s suddenly released a line of permethrin-treated clothing under its WindRiver label this past spring, it came as a huge, personal surprise. For several years, I had been questioning why Canada was reluctant to approve insect-repellent clothing while it was available everywhere else in the world.

I even posted  blogs about this frustrating issue—Ticks, Permethrin and Canadian hypocrisy (April 17, 2017) and Permethrin-treated clothing arrives in Canada (June 14, 2018).

While my primary interest is hiking in the Canadian Rockies, these postings attracted a flood of responses from across Canada. I was even interviewed about the issue on CBC Nova Scotia (“Why you can’t find anti-tick clothing for sale in Canada…” June 23, 2018).

It was obvious many Canadians were concerned about the lack of permethrin-treated clothing in this country, particularly in areas like the Maritimes, Ontario and Manitoba, where tick-borne Lyme disease is most prevalent.

I had a lot of questions about how Mark’s had made its breakthrough with Health Canada, specifically the Pest Management Regulatory Agency (PMRA), so I contacted head office in Calgary.

After an hour-long interview Iain Summers, vice president of innovation with Mark’s, I discovered the company had spent a frustrating decade trying to get approval for its WindRiver No Fly Zone line. And when it finally did come through, the PMRA demanded the clothing be lined with non-permethrin fabric and that Marks couldn’t mention anything about its effectiveness against ticks.

But despite these hurdles, Mark’s forged ahead with the release of its No Fly Zone line this past spring. And from what I can tell, the response has been positive.


Fit, comfort and cost

I had already ordered a WindRiver No Fly Zone ball cap when it first came available online. And Mark’s sent me a No Fly Zone shirt and pants to test as well.

Without any preconceived bias, I am very pleased with the fit and features of my WindRiver outfit. I have a large head, and the ball cap is the most comfortable and ample I’ve ever worn (it is my favourite cap regardless of the bugs).

And I was surprised by the comfort and features designed into the shirt and pants. I even appreciate the lining, which allows me to easily slip in and out of these clothes.

However, I was worried about the PMRA-required lining during hot weather. But after wearing the full outfit hiking and working in the yard in 30-degree-plus temperatures, it didn’t seem a huge problem.

Admittedly, the clothing is best designed for evenings around the campfire and working in the bush, but I won’t be reluctant to wear it when I’m back on the trail. The generous sizing provides good air circulation, and the synthetic material doesn’t absorb perspiration or stick to your skin, so you dry off quickly in the shade.

Permethrin-treated clothing is understandably more expensive than regular outdoor wear. But though I’ve shopped for and received some good deals abroad, the Mark’s line is very competitively priced. In fact, treated tops and bottoms in the U.S. are more expensive, particularly in Canadian dollars.


Effectiveness in repelling mosquitoes

As mentioned in my previous postings, I have a fair amount of experience with permethrin-treated outdoor wear that I’ve bought in the U.S., UK and Spain. So I know pretty much what to expect. And there are no surprises with the WindRiver line.

Initially, there was very little “halo” effect with the cap, shirt or pants when I encountered swarms of mosquitoes. In other words, mosquitoes did buzz around me and even light on my clothes, but these “explorers” didn’t linger long and soon buzzed off. And there seemed to be fewer “explorers” after the initial attack. (This is a subjective analysis.)

Anyway, I can’t imagine any mosquito biting through the cap, shirt or pants (permethrin treatment and the double-lining pretty much insures that). But I still had to use repellent on exposed skin, face, neck, ears, and hands (Picaridin is my choice, but DEET and Oil of Lemon Eucalyptus are effective as well).

Testing Mark's permethrin-treated clothing

The shock cord designed into the cuff of Mark’s No Fly Zone pants provides an excellent seal against ticks crawling upwards to bare skin. Brian Patton photo.



This is a subject the PMRA doesn’t allow Mark’s to talk about. But I’m under no such constraints. I consider the WindRiver clothing design, particularly the pants, an extremely effective tool in guarding against black-legged ticks and Lyme disease.

One of the features that Mark’s doesn’t mention in its description of WindRiver No Fly Zone pants is the shock cord contained within the pant cuffs (probably due to PMRA restrictions). This is the most efficient shock cord I’ve ever encountered on any outdoor pants. It provides a very snug but comfortable seal around the ankle, and along with the permethrin-treated cloth, creates an effective second line of defence against ticks moving upwards to bare skin.

Where I do most of my hiking, wood ticks are the primary nuisance. There are a number of trails on south-facing slopes in the Bow and Columbia Valleys where I always come back with at least one wood tick between late March and mid-June. Wood ticks are a lot easier to spot than deer (black-legged) ticks and less dangerous. My WindRiver No Fly Zone clothing arrived after the peak of the wood tick season, but you can be sure I’ll be testing it next spring.

No, there is no 100% guarantee that a tick can’t gain access to your flesh, and if it is a black-legged tick, transmit Lyme disease into your blood stream. But using well-designed, permethrin-treated clothing will improve your odds of travelling tick-free by about 95% (my educated estimate).

And if the PMRA doesn’t agree with this, maybe they should check out recent studies carried out in the U.S. (“Study confirms this method of repelling ticks really does work” CBS News, May 25, 2018.)


Yes, you can saturate your clothing with DEET and get the same protective effect. But how many people are willing to do this every time they step out into the bush, backyard or onto the trail? It is so much easier to slip into pre-treated, scent-free clothing that is proven effective for pretty much the lifetime of the garment.

Until the PMRA takes a more realistic approach to the use of permethrin-treated clothing and sprays designed for treating same, Mark’s WindRiver No Fly Zone attire serves as the best defence against insects and ticks that is readily available in Canada.


  1. pam

    Thanks Brian,
    I agree 100% with your comments. Why our gov’t was such a stickler????
    The pants were effective in the Sunderbans and comfortable…
    although warm and humid +30, the pants were no issue as they seem to be cool too maybe because of the lining and light material.
    I bought the shirt and hat for this season.
    Glad to see a non bias opinion

  2. Jurek

    Many thanks for this informative article about windriver mosquito repellant clothing at Mark’s Work Warehouse.

  3. Anand

    Were you able to test the clothing against ticks this spring/summer? How did it hold up?

    • Brian

      Yes, I have. Though my tests are strictly anecdotal. There are a number of lofty, south-facing trails near my home where I inevitably come back with a wood tick. I hiked these trails much more than usual this spring but didn’t return with any ticks. All my hikes were completed in Wind River No Fly Zone attire. (I suppose it would’ve been more scientific had I rolled around in the grass.)
      I’ll be posting an evaluation of No Fly Zone and Insect Shield clothing once I’ve waded through a week or two of mosquito season.

    • Anand

      Thanks Brian for the reply. It eases my mind to know that you didn’t come back with any ticks. I just bought a pair of No fly zone Pants and a full sleeve button up shirt a month ago as I do a lot of wildlife photography as a hobby. So I’m always in areas that could potentially have ticks. I’m also considering getting some Rynoskin base layer to put underneath my no fly zone clothing. As you can clearly see, I’m pretty paranoid about deer ticks.

      Thank you for your testing. Cheers.

  4. Markus

    Thank you for your article. Are there any differences comparing Mark’s permethrin-treated closing to the NosiLife from Cragshoppers?
    Do you think they are good for travelling to a Malaria area?
    I am rather better protected and I do not mind to be really warm and wear multiple layers of clothing which I would treat with permethrin as well.Do you have any suggestions what to wear in order to prevent mosquitoes from biting through clothes?

    Many thanks.


    • Brian

      I’ve tested Marks No Fly Zone, Insect Shield and Craghoppers NosiLife (UK version) and haven’t seen any difference when it comes to mosquitoes. Loose fitting shirts and pants commercially treated with permethrin should be effective in preventing mosquitoes from getting to your flesh (occasional penetration possible with tight-fitting permethrin-treated t-shirts). No extra layers or permethrin treatment should be necessary. But you’ll still need some sort of repellent for exposed skin, like face and hands. My preference 20% Picaridin rather than 30% DEET, though both are effective at those concentrations. And depending on where you’re staying, a bed net might also be useful.


    Iam a hunter and spend hours in the bush every spring and fall is there a company in Canada that makes clothing for us ?If not why not.Here is your chance

  6. C

    What happens to the protection when the clothes are washed?

    • Brian

      All permethrin-treated clothing is supposed to retain its bug-repellent quality for 70 washes. However, there are indications that effectiveness starts to fade before that (I avoid frequent washing). I always wash and store permethrin-treated clothing with other permethrin-treated attire. Though Marks says No Fly Zone clothing can be tumble dried, I always hang these items on the line (similar to what is suggested by Insect Shield).

  7. Mark

    Thanks for this informative article, Brian.
    Mark’s is now advertising this clothing WITH the anti-tick, anti-mosquito descriptions. Can you let us know what has changed that allows them to do this? Is the current “No Fly Zone” line the same as what you used? Did the PMRA relax their requirements? Something else? Thanks!

    • Brian

      In the past, the PMRA wouldn’t allow Marks to advertise that their clothing was effective in repelling ticks. The agency obviously relented on this ruling. No Fly Zone permethrin-treated attire was always considered an effective tool for repelling ticks in the U.S. I’m happy that the PMRA is finally allowing Marks to advertise the same here.

  8. Alina

    I just got a pair and I thought I better google it first before taking off the tags. I was concerned that they might be too hot. I am really surprised to see that you used them in 30 plus temp while doing gardening and you were not hot. Really?
    Thank you

    • Brian

      My original tests with Mark’s No Fly Zone lined clothing were midsummer in British Columbia under very dry conditions. I’ve since experienced discomfort when humidity is higher and found the clothing less comfortable. I also have Insect Shield clothing that I brought in from the U.S. and certainly prefer this unlined attire when things get toasty. I hope to post a final review of permethrin-treated clothing and repellents this summer.

  9. David

    Just bought a shirt and pants. had wood tics on both and they stayed on the fabric for over 5 min without any effect. Finally got bored watching them and picked them off. plenty more during the day. I have a vid of the tic on the pants but too big to send. I have a photo of a tic on the shirt but can’t find a way to attach. Thunder Bay Canada

    • Jackee

      Well that is disheartening to hear. I just bought Marks No Fly Zone hiking pants and have not even had a chance to try them out. Is that the brand you are referring to?

  10. buc shields

    when i wash these clothes what happens to the protection

    • Brian

      All commercially treated clothing is supposed to remain effective through 70 washes. Consumer Reports testing indicated a slight drop-off in effectiveness after 25 washings. But don’t expect this clothing to stop ticks and mosquitoes from “exploring”.

  11. Steph

    Hi there, are the clothes supposed to be washed inside out?

    • Brian

      No, you don’t need to wash Marks permethrin-treated clothing inside out. However, all permethrin-treated clothing should be washed separately from non-treated clothing.

  12. Sheila Picknell

    I am very allergic to mosquitoes, I have swollen up to the point of having to be on an antibiotic. I am the type of person if there are 100 people and 1 mosquito, it finds me. I am very happy about the quality and performance of my pants, shirt and hat. I love to be outdoors enjoying hikes, climbing and sitting out in the evening. I highly recommend them to my friends. I have been out on a trail and people have said, “they are flying all around me, but they do not land or bite. A very worthwhile investment. I great bonus that they are good for up to 75 washes I was told.

    • Grizzlydueck

      I’m a hard core shed antler hunter. I’m out 10 hour days for our tick season.
      Some years for weeks at a time. Bad spots we have over a 100 ticks a day
      Since running these no fly zone pants I haven’t had a tick yet !
      My dog gets the advantix drops for April and May.
      He doesn’t get ticks anymore either.
      It is truly such a game changer especially for the shed hunters.
      I wash my pants only if truly dirty. Air dry and put into a grocery bag wrapped tight. Then I still keep it out of the cab and away from pets and humans.
      Happy trails

  13. Linda

    I had an anaphylactic reaction to the product.

  14. Stephen Morris

    Brian, thank you very much for the informative review. Looks like this new line of clothing ticks all the boxes.

  15. Dale Parker

    I read your report with interest but your methodology is anecdotal and therefore your conclusions are likely flawed. Prior to the ban we used Sawyers Permethrin Spray to treat our hiking pants and socks to reduce picking up ticks. In some of the areas we frequent I have seen 30+ ticks/sq meter and likely a lot more that I could not see/count. We did tests of putting ticks on our socks and pants to see how they reacted to treated and untreated areas. On untreated areas once they latch on to the clothing most immediately started moving up the pant leg. Speed varied with temp. On treated areas after a few cm/inches of contact the ticks began to behave erratically, stopped moving and then fell off dying. Have you/or anyone done observations on how ticks react to these commercial products?

    • Brian

      Unfortunately (?), we don’t have a good supply of ticks in our neck of the woods. Your tests confirm what I would expect. Both ticks and mosquitoes will “explore” permethrin-treated clothing, but are thwarted in their quest for blood. Tests on commercially-treated products in the U.S. have produced similar results to yours. Check out https://www.cbsnews.com/news/tick-repellent-permethrin-clothing-really-works-study/

  16. Dale Parker

    Brian: It always concerns me when I am told to check out a “news” story rather than being provided a link(s) to the primary literature. Journalists are notorious for “creating a story” of the facts by emphasizing certain parts, neglecting other parts, creating errors and half truths etc.

    • Brian

      As stated in the CBS story, the study in question was published in the Journal of Medical Entomology (Oxford Academic). By googling that journal and searching “permethrin clothing” you will discover scores of scientific studies conducted over the past 40 years on permethrin-treated clothing, including the one quoted by CBS.

  17. Eva

    Marks No Fly is also very effective against tse tse flies. I’ve worn their clothing on safari. Tse tse flies normally love me, but they kept their distance. Permethrin is commonly used in East Africa for warding off tse tse flies. One note is that the permethrin washes out after so many launderings. I think it’s 50 times, but am not certain. It should be noted on the label. In summary, it’s a super product.


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