I think there are foggers made to kill spiders.
What kind of spiders are they? That will make a difference. I don't think foggers work for Hobo spiders.
I watched Infested on Animal Planet the other night. A couple used foggers and they came home and lots of dead spiders. Something weird happend, though. They started getting overrun with Hobo spiders. Come to find out...when they used the foggers, the foggers killed the other kind of spiders that were keeping the hobo spiders at bay.