I always have trouble with them getting under the doors and making webs around the garage door sensors. Black widows like those low-lying areas, though I see those more outside under wood piles, etc. I've used Ortho Home Defense in the past, but haven't sprayed it much since we have 2 young kids and they're always dropping food on the ground/floor.
I'm not a spider fan, but gotta say....we went on vacation 2 weeks ago. I keep my trash can about 15 feet from my garage doors...I probably cooked some kind of meat and bagged some scraps up in the trash, which didn't run until after we were gone so I just left it until we got back. My guess is some maggots hatched and went crawling toward the garage and hatched in there. By the time we got home, there were a bunch of flies flying around the garage (50+) and a bunch of dead flies spread across the floor (50+) and ample spider webs on the doors that didn't exist there before. I actually preferred cleanup of the webs vs the dead flies that were scattered. In any case, a leaf blower worked wonders....I highly recommend installing a solids-based epoxy floor coating....not much will stick to the floor and you can clear messes pretty quick.
