Short answer: Yes! I love mine! I also have a very stylish hat that isn’t treated, but keeps the insects from biting my neck and head.
And now, to qualify my answer with a bunch of facts and disclaimers. :)
I talked before about personal repellents like DEET and other compounds you apply to your skin. You can also wear clothes treated with insect repellents, the most common of which is Permethrin.
Repellent-treated clothing is commonly used in the military–you don’t want to be covered in greasy lotion, or stop to put it on, if you are in a combat situation! This has lead to the treated clothing being marketed to a wider audience.
There is a catch: the stuff is expensive. A treated shirt can run up to $60, and will last for up to 70 washings, depending on your brand and use. On the other hand, it’s worth it to me to buy a heavy-duty pair of pants and know that I won’t get bitten on the butt anymore. (Mosquitoes can bite through most fabrics if they are taut to the skin–as happens when I’m bending over weeding in my garden.)
If you think of the price as West Nile Virus Insurance, it might make it a little more palatable.
If you purchase permethrin for DIY treated clothing, Follow. the. Instructions. For. Application. Do not apply Permethrin to your skin directly.
Will it repel other biting flies too?
Yes and no. Most are effective against ticks and midges.
Permethrin treated clothing isn’t repellent to ALL biting flies–this study from Iran, for example, found it ineffective at preventing transmission of leishmaniasis. If you are traveling outside the US, you need to carefully study what might want to bite you, and plan accordingly.
Is it safe?
Don’t confuse pyrethrin and permethrin–they are similarly spelled, and have similar chemical profiles, but do have different formulations and toxicology profiles. Pyrethrin applied to garments is unlikely to last long.