We use the 20 ounce water bottles after they have been emptied let them dry out we keep the lids and drill a very small hole in the bottom of the bottle, then fill them a quarter of the way with mothballs and hang them a few inches off the ground about every ten feet around our coops. We shake them once a week to increase the scent, We use the water bottles so has not to have the mothballs sitting around where any animal can get to them has mothballs will kill anything that ingests them, usually we only have to fill them once a year. We also buy the mothballs from our dollar store has it is cheaper than the bigger chains.