They do die out within a year up here in the mountains in my part of California ... thank God. I've had a few nests in rather inconvenient places.
One year I had yellow jackets build a nest behind the flashing behind my front door. Of course, I found out the hard way. I went out and slammed the screen door and they came after me and got in my hair. I ran down the road screaming as I tried to unbraid my hair to get them OUT ... a neighbor helped me. That night, I used my pump sprayer and sprayed the whole door and siding with vinegar and they moved the nest. I guess they didn't like the smell of the vinegar.
It was a nasty experience. I wouldn't use vinegar on a plant, but I've used it on the house and my wood pile for spiders and it has been quite effective.
