Leaf-cutter bees are solitary bees that construct their nests in little holes found in things like wood: In the previous picture, the bee used driftwood, which she’d found on our porch, but anticipating the need for additional nursery-space, I placed an old mud-dauber nest nearby: To my total delight, she took the bait and I watched as she ferried supplies inside. (In this case, a tomato skin).