Well, this situation has come to a surprise conclusion. After supper, as soon as it was dusk, I went up to the yellow jacket nest armed with two more gallons of soapy water, and to my utter shock, the nest was dug up and all the yellow jackets gone or dead!

I just stood there, dumbfounded, with the gallons in my hands, speechless, my mouth agape, I couldn't understand or believe it. They were there yesterday! Based on the damage, I'm guessing it was a raccoon, which according to Justin Schmidt (of the Schmidt pain index fame, I happen to be reading his book right now) are the most common predators of yellow jackets in North America. The nest wasn't very large, somewhere between a softball and a volleyball in size. I'll inspect it in more detail tomorrow when it's light. So, I guess that's it. My advice to anyone else with this problem is to pour 1 gal. of soapy water down the hole and wait for the predators to do the rest!
