I have used Preventive for the past year, after the initial visit where the pest tech came out and sprayed inside tech whole house and then power sprayed the out side, attics and crawl spaces, we saw our sugar ants, wolf spiders and little black thing's ( i have no clue what they were but they were about the size of a pin head lol) disappear. We had no problems with re invasions. We had a bi monthly service just to keep control of our borders so to speak, and out tech was always willing to go back and spray anywhere i thought i might have seen 8 legs run across the floor.
Preventive Pest Control offers unlimited free re-service package ( at no extra cost) we only had call to use that once, If you have a bug come back in the house, they will come back and spray for free as many times as needed until the invasion is taken to task. It is a year contract, but I have never had a better company service my home. They have a fantastic guarantee and a referral program.