Leaf Cutter Bee

I have found the dry, rolled up pieces of leaf in dry plant pot compost and wondered what they were all about. Today I watched the Leaf Cutter Bee cut, carry then patiently roll the cut pieces of leaf before burying the leaf tubes in the earth of a terracotta pot. They are apparently cavity nesting and will find a suitable soft dry areas to build cylindrical cells with leaves or petals, each cell is carefully sealed over with a segment of leaf.