PF Harris 16 oz. Boric Acid Roach Killer Powder with Special Lure. It contains 99% boric acid, effectively killing roaches, waterbugs, and silverfish. Simply apply the powder in cracks and crevices, behind walls, underneath appliances, and crawl spaces. The label instructions provide detailed directions for proper use and disposal. This easy-to-use puffer bottle comes with an 8" applicator, allowing you to reach even the hardest-to-access areas. Active ingredient: boric acid. Roaches carry the fine powder back to their nest, eliminating the entire infestation.