To keep opossums from making a home under your deck or patio, its essential to block any entry points that they might use. If you think a mother opossum has already moved in, wait until she leaves her den and then cover the opening with a net or straw. This way, if there are any opossums inside, they can find their way out, but others wont be able to get in. Opossum moms typically carry their babies with them, so theres usually no worry about leaving any little ones behind. However, before sealing the opening, its always a good idea to check for youngsters. If the hole stays undisturbed for a couple of nights, you can safely assume its empty and go ahead and fill it up (7).