Paper bag stuffed with what ... anything in particular?
Just something to make it look like a hornet’s nest.
PS, it does work in most areas depending on how much area you are trying to protect. I have one hung in a camper shell that is suspended from the barn ceiling and there is not a single dirt dobber or wasp nest in it. I convinced someone to put them up in the rafters of his airplane hanger, no wasps anywhere.