Carpenter bees are large, solitary creatures. They get their name from their interesting nesting habits; females excavate a burrow in wood in which to lay her eggs. There are four stages of a carpenter bee's life cycle: egg, larva, pupa and adult. The whole transformation from egg to adult takes roughly seven weeks.
Like all bees, carpenters start out their life cycle as an egg. Before these eggs are laid, the mother bee has a lot of work to do. Using her mandibles, she makes a half-inch hole in a wooden object, excavating the wood for two inches before making a right-angle turn and creating a tunnel that's between four and six inches long. It's in this tunnel that she lays her eggs. She makes an individual brood cell for each egg and deposits food into it before sealing it up.
The next phase of a carpenter bee's life cycle is the larval stage. Once the egg hatches, a larva emerges. This larva is safe deep inside the tunnel its mother dug and sealed inside its brood cell, where it lives off the food that was put there with it. This food source is known as bee bread and is a mixture of pollen and regurgitated nectar.
The pupal phase of a carpenter bee is when it metamorphoses from a larva into an adult bee. During this inactive stage, the young bee is rather vulnerable. However, due to its intricate nest, it's safer than many other creatures that undergo metamorphosis. Unlike others such as moths and butterflies, the carpenter bee larva doesn't have to build a cocoon; rather, it makes its transformation while still in the brood cell.
Roughly seven weeks after first being laid as an egg, an adult carpenter bee emerges. The young bee breaks its way out of the brood cell and leaves its nest to face the outside world. Once the colder months come, it will either return to its old nest or find another disused one in which to overwinter. After emerging the following year, the males will die shortly after mating and the females after laying their eggs.