I use Demon WP at least twice/year. Used to have a bad problem with the black widows in a previous storage location. Wasp spray didn't phase them so I went to the feed store and they introduced me to Demon WP. Haven't seen a live spider in storage since, but tons of other dead bugs that cross the Demon perimeter.
"Things turn out best for those who make the best of the way things turn out" - Zachary Troy Schrah - a young man with vision far beyond his years.