Lots of yellow jacket nests here in Oregon. Best way Ive found to kill them:
Make a 12"x12" wood frame out of 2X2 lumber (gives it some weight) and staple some window screen to frame. Early morning cover the nest entrance with the screen. Add 1/2 cup dawn dish soap to 5 gallon bucket then fill with water. Dump into nest, repeat if necessary.
The soap suffocates the bees.
Also skunks love to dig up and eat them.