This image shows Carpenter Bee in it's nest.
This is the underside of the ceiling of backyard shed.
You see the holes made, the golden excrements and the Bee.
Please, click on the Image to Enlarge it and View the Image Details.
These large Bees are often mistaken for being Bumble Bee. Carpenter Bees burrow in wood in a solitary nesting hole.
The Carpenter Bees make significant damage to the wood where they nest and they also pose a stinging threat to the residents.
You may notice carpenter bees coming and going from holes in the fascia board, deck posts, or other wood structures.
If you suspect Carpenter Bees burrowing in a fence post or other wooden structure, try to look at the entrance holes. A carpenter bee makes an entrance hole slightly bigger than her body, or just about ½ inch in diameter. The first 1 to 2 inch of the tunnel is usually made against the wood grain. The bee will then make a right turn and extend the tunnel another 4-6 inches in the direction of the wood grain. Carpenter bees will often excrete their waste before entering their nest, so you might see yellow or golden stains on the surface of the wood near the entrance hole.
Since excavating a tunnel requires a lot of energy, a female carpenter bee will prefer to refurbish an old tunnel to digging a new one. If carpenter bees are allowed to tunnel in the same structure year after year, the cumulative damage could be significant.
Carpenter bees prefer to excavate untreated, unfinished wood. You can discourage, if not prevent, carpenter bees from nesting in a wood structure by painting or staining the untreated wood elements.