For most of history, lice have been more than just a terrible annoyance. They can spread a terrible disease called typhus – which was quite prevalent up until 15 years ago. Chemicals like permethrin have managed to make it far easier to get rid of head lice and the diseases they spread than.
But since head lice are becoming resistant to poisons like permits rent, there are new ways coming up. You'll even find expensive salons everywhere that specialize in how to get rid of head lice. They have quite a market. There are at least 15 million head lice cases in America alone every year.