Permethrin is easy to test. In the warmer months, go outside at night and find a spider, spray it with Permethrin. It takes 10 to 15-seconds but then the spider starts jumping around like crazy and within a min or so it drops to the ground.

Also to see how well it last, I have a few windows that face the back of my property, spiders love to make web across these windows all summer. I spray around the window with Permethrin and for the next month no spiders. I also have an old iron fence post with a cement cap on it. On the side of it there is a hole, wasp love to make a nest inside the fence post and go in & out the hole. I coated the hole very liberally with Permethrin and no more wasps there anymore. I don’t know if they died inside or could not get back in but they are gone


Permethrin Is great stuff.