(18 Rescue Reusable Fly Trap Attractant Refills) Catches: Common nuisance or filth flies including house flies, cluster flies, false stable flies, blow flies, bottle flies, flesh flies and others. How it works: The RESCUE! Fly Attractant works inside the RESCUE! Reusable Fly Trap to lure common nuisance or filth flies. Each refill packet contains one application that generally lasts two weeks to a month. Just drop the water-soluble pouch into the trap jar, add water to the fill line, replace the top, and hang or place the trap outside near a fly source. The flies drown inside the trap.