Any treatments should be done at night, because they are all in the nest. They don't see well at night and your chances of being stung are greatly reduced.

Treat the nest with a pyrethrum aerosols such as: PT 565 Plus or CB Extra

Pyrethrum forms a gas which will fill the cavity, killing the yellow jackets.

Wait unil the aerosol is dry then dust in the opening with Pyganic Dust or Delta Dust .

These dusts will leave a residue to continue to kill for months and eliminate any hatch outs.

With a little care and caution, yellow jackets can be easily and safely eliminated.

Directions

1. Spray opening at night with pyrethrin aerosol about a 15 second blast
2. Wait until aerosol is dry(10-15 minutes), then dust opening with Pyganic Dust(faster kill with the pyrethrin aerosol)or
   Delta Dust(3 weeks -a little slower kill- with pyrethrin aerosol)

For complete results use Walt's Yellow Jacket Kit(CB 80 and Pyganic Dust and duster)