Simply cut the clear plastic circle at the very top following the scissor symbols and dashed lines. Add water to the fill line and it s ready to go. Flies find it fast! The attractant packet inside the bag dissolves and activates when you add water. Lured by the scent flies enter the trap through the yellow top cap and drown in the water. Unique Features & Benefits Complete with fast-acting lure Just add water and hang outdoors Never touch the bait or the flies Disposable Catches up to 20 000 flies (yes we counted them all!)