Turns out the Chrysanthemum plants aka "Mums" have a chemical that disables ticks, mosquitos and other bugs. The synthetic form of this was developed back in the 70's and is called Permethrin. It's rated as safe by the FDA, and it's not very easily absorbed or toxic to humans,
It's recommended you spray pure Permethrin on the outside of your clothing not your skin because it can cause itching and redness on some people although there are some products designed to be used that way. Ticks are incapacitated from biting You, and soon die from contact with permethrin.
Before we head out on an excursion, we spray our longsleeve cotton shirts liberally, and let them dry over night, You can buy Permethrin spray a lot of places. Just google it.