About 140 species of native bees make their homes in preexisting holes and woodpecker drillings; they are naturally drawn to the bamboo tubes in this bee house which faces the morning sun. You can see that female bees have laid eggs in some of these tubes, filled the tubes with nourishment, and sealed off the entrance so the young can grow safely.
A female mason bee, for example, will back into one of these tubes, lay an egg, deposit pollen and nectar (food for when the egg hatches), and build a wall of mud to create a brood cell. She then repeats this process about 10 times, creating a cell for each egg.
Leaf-cutter bees build their egg cells with pieces of leaves. They build multiple egg chambers per nest hole and deposit an egg in each chamber with a bit of pollen, nectar and saliva to nourish the larvae. The varied-sized tubes attract different kinds of bees.