Thank you for a reasonable suggestion, but these bees are swarming around the
nest area and it wouldn't be possible to capture one. I realize the
identification I gave is vague; I guess I'm just looking to narrow down the
possibilities so I can do some more online research. I've tried searching for
"ground-nesting social bees" and the like, and have had lots of hits but no
real means of identification. (And it may not matter.....!)

By the way, I'm in the northeastern USA, if that helps with anything.

Thanks again,
Carol

Can you describe it in more detail. coloration,flight,size,etc?