You have leaf cutter bees. Leaf cutter bees are a type of Solitary Bee. They use the cut pieces of leaves to build there nests. They do not drill holes in wood. They only look for holes that are already there or if there is wood that is decaying and soft they can excavate it to form a bed for there eggs. They are much more efficient than Honey Bee's at pollenating. You can read more about them here.