This sounds crazy, but it works. Get a couple plastic owls for the yard or a tinish kind to hang from a tree. My son had snakes like that and I took him a plastic owl with a bobbly head and a metal artistic one to hang. In a matter of days the snakes were gone. Lowe's has them. They put them on stakes on our golf courses and the snakes are happy to stay in and around the ponds. Black ones here in FL keep any poisonous ones away. I have an owl sitting on my grill in our courtyard and an owl on a rock in the front. Good luck!