>>2752905Woodsmoke is very effective in repelling insects, and ancient Europeans in all likelihood had a fire going on at all times when they were not moving around, like herders and hunters still do in places where it's not forbidden by law. They also wore clothing that covered most of their body, including specific anti-mosquito clothing like hoods and coifs. And if those two things were not enough, it's possible to use tar oil on the skin, which is a natural repellent, although it was probably only used in extreme cases and is considered a carcinogen now as far as I know.
