During the spring, people often notice large, black bees hovering around the outside of their homes. These are likely to be carpenter bees, named for their habit of excavating holes in wood, in order to rear their young. Carpenter bees prefer unpainted, weathered wood, especially softer varieties such as redwood, cedar, cypress and pine. Carpenter bees resemble bumblebees, but typically have a shiny, hairless abdomen. 

a Capenter Bee drill a hole of wood pallet and making the nest.