Bed Bug Black Powder is a long lasting powder kills even the toughest pyrethroid resistant bed bugs. 4oz puffer bottle comes complete with applicator brush. Using the attached applicator brush, apply dust evenly as a light coating creating a barrier through which bed bugs must crawl. Electrical switch plate covers can be removed to allow access to voids, but dust shouldn't be applied directly in the electrical boxes. Treat the mattress and box spring, paying particular attention to tufts, folds and edges.