Picture of hole.

Carpenter bees. They come back. I spray my barn 2x a year.

Yes; carpenter bees. You can also buy or build a trap or traps like THIS. They actually work. They seem to do better if you leave old dead bees in them. You can also smack 'em with a badmitton racket or something!You may look like an idiot while you miss them, but theraputically satisfactory when you smack one of them.

Carpenter bees are big and black similar to bumble bees but bumble bees won't be hovering around wood but rather hanging around flowering plants like regular bees.