Well no science behind it... but an interesting way of keeping mossies away.

survivalschool.us/preventing-bug-bites-in-the-woods/

Southeast there were about three methods used to deal with mosquito, often all in conjunction with each other. There was a combination of plants and pitch rolled together and burned to make a kind of repellant. This burning combination would be worn in a head band or sometimes around the neck in a small container of leather. The substance would smolder for a long time and give off much smoke. Other methods were much more simple. A thin coat of mud would be applied to exposed skin or sometimes ash from fires mixed with water. Of course dusk and dark would be the peak times and they would usually be around camp fires which can work if they are supplied with some green vegetation for smoke.
But probably they became somewhat accustomed to the annoyance overtime and it diminished the longer they were exposed. Of course many areas of the Southeast have mosquitoes so thick that they make it impossible to take a breath without breathing in mosquitoes at certain times of the day during certain seasons. This would require serious effort to operate in this environment.

Staying away from dense green vegetation, close to stagnant water, during the peak mosquito times was probably very much apart of how they dealt with it.