There are several types of bee that nest in the ground, Ken. I'm guessing that's what she means.
Anna, the bees probably won't harm the plant at all, since stags are pretty solid in the middle and couldn't accommodate a large colony anyway. Ground nesting bees tend to be non-aggressive too, so I think I'd be inclined to just observe them for a while before taking action.
It's also possible that something as simple as dousing the plant with the hose a few times will discourage them if you really want them gone. I'm a big proponent of trying the simplest thing first . ..
Bees tend to nest in dry areas, I think.
