You can also use a plastic container to keep cats inside. Shoe box size works well. Line the bottom with paper towels. You must clean every day. Monarchs require fresh milkweed. So you must keep the milkweed moist. The best way to do that is is to stick it in florist foam. Do not use a shallow dish with water. The cats will drown.
There is lots of information online about raising different types of cats. I found monarchs to be difficult. I raised Black Swallowtail for a number of years.
