The carpenter bee is just over an inch long, and weighs only a few geams. These bees are mostly female, and they drill perfectly round 3/8 inch holes with their mandibles. This is usually in the wood along the eaves of homes. They do not eat the wood but rather make tunnels through it in which to lay eggs and raise young. While carpenter bees are strictly considered "wood-destroying' insects, the damage they do is typically limited to surface wood, and they are not likely to do any damage to the structural, or weight bearing, wood of a house. They don't get into your house to destroy studs, rafters and joists.
Carpenter bees are solitary insects, but they will often nest in close proximity to other carpenter bees. Left untreated, they can grow to large numbers and eventually completely destroy the wood in which they are nesting and tunneling.