I have a Certified Wildlife habitat for my yard. Other than gophers in my day lillies, almost anything is welcome to live in my yard. I saw some mason bees at my nursery the other year, but they were mighty expensive. My former spouse got some in Tennessee, and kindly sent me a package over the winter. Now that the fruit tree buds are starting to color, I decided to put them out. I read on the internet how to make tubes out of parchment paper for new nests, and looked at pictures of expensive nest boxes. For bees? Really? Surely cardboard should be cosy enough. I need to get some chicken wire and cover this so the birds don't mess with it, I read, but otherwise, it is ready for spring. So, we shall see what happens. I'll let you know.