catchmaster x-large outdoor disposable fly bag trap - bulk pack of 4 fly bags catchmaster the disposable fly bag trap is easy to use – just add water to the included fly attractant. specially-formulated lure is designed to attract a broad range of fly species and is long-lasting. catch hundreds of flies! these catchers are great for hanging near a horse ranch, farm, patio, house, garage, office. these traps are an amazing catcher for both indoor/outdoor use.