This year I had real problems with Yellow Jackets. I used traps to help resolve the problem. The traps caught a lot of yellow jackets, but the problem continued. I also poisoned the Yellow Jackets, using soft cat food and flea poison. (You'll need to protect the poisoned cat food with some sort of means, to prevent cats or dogs from eating it.)
That also seemed to work, but the problem continued, to a lesser degree. Only our recent cold weather seems to have done the job.
One of the BK's on the forum suggested I start earlier in the year, with the hopes of getting them before they build up. Perhaps, even poison the queen before she starts laying eggs. If you do a little searching, you'll find that you can make up your own traps using plastic bottles. That will save a few bucks.
Good luck with the Yellow Jackets.
Regards,
Tucker1