RESCUE!® POP! Fly Refill works inside the RESCUE!® Reusable POP! Fly Trap. Each refill packet contains one application that generally lasts two weeks to a month. Just drop the water-soluble pouch into the trap container, add water to the fill line, replace the top, and hang or place the trap outside near a fly source. Use with RESCUE!® POP! Fly TrapFlies get in, but not outNo killing agents; insects drownNon-toxic mode of actionDissolves and activates in water