I really, really, really hate these guys.
I've learned through painful experience to carefully watch my backcast when fly fishing.
I have hooked trees that were attached to nests and I've run over some ground dwellers while mowing the lawn, another good reason not to mow the lawn.
Anyhow, here's a tip on how to get rid of yellow jackets, from a fellow in Asheville.
Rubbing alcohol, cheap and effective. Pour a bottle of Rubbing alcohol into a large cup, this will allow it to be poured quickly. Pour it into the hole at night when they are nesting to quickly saturate the nest. Most that get a good dousing will normally freeze to death! The evaporation of the alcohol pulls heat out of them too fast and chills them to below a survivable body temperature. One or two applications usually does the job. You can put it in a spray bottle and knock out ones flying around inside your screen room or house. They will fly at you but quickly drop to the floor when hit with the mist. Coat them once or twice and they will certainly go defunct.
Best of luck mike -- Michael Fortune Green Hill Urban Farm 40 Green Hill Ave Asheville, NC
A tip of the fly fisher's (and landscaper's) hat to you, Mike.