I've used diatomaceous earth to thwart ants climbing into my bird cages in the past. It works great. I even sprinkled it all the way around my house to keep them out. Insects don't want to walk through it. It's microscopic, glass, single-celled organisms' skeletons. It's like walking through glass for insects. To apply it to your body you wouldn't even need food grade DE. It's basically just dirt made of diatoms. There's even a mine near where I live. It's just white, powdery dirt.
Female, 5'3", 50, Max squat: 202.5lbs. Max deadlift: 225 x 3.