Marilyn, once the spiders check in they don,t check out, they are stuck until they die. I bought them at Canadian Tire, it's an everything store, hardware, lighting, gardening, sports, kitchen ware, tires, get your oil changed while you shop!
Great place!! They cost $2.39 and there's 4 per package, they are made in the US, so I suggest you try places like Home Depot, Lowe's, or seed stores, I found them in the section where they sell mouse traps and the like, do not buy the large ones scented with peanut, they do not work as well.