For what it's worth....I managed to rid my yard of a nest of yellow
jackets in an environmentally friendly way.  I waited until dark, after
the ground bees had gone into their nest for the night, and then just
covered the hole with a clear glass bowl, making sure that there were
no gaps around the edges.   For a few days I could see bees inside the
bowl trying to escape, then eventually, no more activity.  Not very
humane, but it was effective, at least it was in this case!
Eileen Gregory