Combat ® Source Kill Small Roach Bait. Easier and cleaner to use than sprays or foggers—no monitoring needed. Covered bait station needs no activation and contains no vapor, fumes or odors. Slow-acting formula allows insects to carry it back to the nest, killing other roaches and eggs for long-term control. Effective for up to three months. 12 Packs per Case. 12 Baits per Pack.