Carpenter bees, also sometimes known as wood bees, don’t have a great reputation. That’s because they are the ones (the female workers, again) that bore into your wood and make a hole as neat and clean as if it was bored out with a power drill. The presence of sawdust on sills or stoops is an indication you should look for a hole, which is the female’s reproductive nest.
She lays her eggs, females first and males last. The bees emerge from the hole in the spring, leaving in single file. The males go out first so they can be ready to mate with the females when they leave the nest.