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