Google Viper spray, safe for wood finishes and last about 6 months before retreatment. If it is rainy, I retreat every 2 months. I mix it with Martin's IG, it prevents larvae from maturing.
We have a scorpion and flea problem because of sand and oak trees, the youngest is the only family member that literally gets eaten alive by fleas and chiggers, so I aggressively treat the areas right around the house, chicken coop, farrowing shed, swing set and trampoline.
Fire ants hate the stuff as well, I keep a small hand sprayer in the Ranger and on the tractor for spot treatment.