Carpenter bees do not live in hives, but rather they are solitary insects. The female bores holes into rough, unfinished wood to lay her eggs. Holes can be as shallow as six inches and as deep as four feet. It is easiest to look for carpenter bee holes around the wood of your house in the late summer when the bee nests have matured. Female bees have stingers, but they are not aggressive.
Look around for male carpenter bees. They hover around the female's nest. Male carpenter bees do not have stingers, but they will try to intimidate you by flying at you and buzzing around your head.
If you notice male bees, look on the ground or on any horizontal surfaces for what appears to be coarse sawdust. This is called frass. It comes from the hole the bee drilled.
Look above the frass, and you should see a perfectly round hole 3/8 inch in diameter. This is the carpenter bee's nest.
TL;DR (Too Long; Didn't Read)
Sometimes you will see more than one hole where the bee nests. These could be old nest holes.
Even though queens aren't aggressive, always be careful when looking for bee nests to avoid stings.