Permethrin for ticks. Spray your clothing and boots (don't spray your undies). Deet for your skin.
Ammonia for bites, reduces the itch, and kills chiggers where they are dug in under the skin.
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Again, the old wives tail that chiggers are UNDER your skin, surfaces yet another time. By the time you feel a chigger bite itch, the insect is LONG GONE, plus, it was NEVER under your skin.