Harris Boric Acid Roach Power with lure kills Roaches, Palmetto Bugs, Waterbugs and Silverfish. The included powder duster reaches into cracks and crevices where insects hide. Harris Boric Acid Roach Power continues to kill roaches, palmetto bugs, water bugs and silverfish for weeks after application as long as it’s kept dry. Insects coming into contact with the powder will die within 72 hours after initial contact.