Voted Best Answer
Dec 11, 2014 - 07:26 AM
Next - after you have officially extracted all the spiders you can find, spray the basement perimeter and also under the floor joists, beams etc, if exposed with either Demon WP or Suspend SC. These products will leave a residue that will help to control the spiders for 3-4 months. Repeat the process a couple times a year or more often if needed.
You can also use Sticky Bug Traps to help capture the spiders in between the treatments. You can place them along the walls and even staple them to the upper corners of the basement along the beams and joists. Replace them as the get full.