I've got a lot of jackets around. They hover around the entrance and get chased back out, but if a bee falls on the ground they are on her so quick! It pisses me off so much, I've taken to stomping on them. The more you kill, the more they come to eat their deceased brothers and the more I can kill! It is hard to stop!
We had a yellow jacket nest in the roof and called an exterminator. He said the hanging traps with pheramone were essentially useless since each nest is currently producing 150-200 young EVERY DAY!! So unless you are trapping 200 a day, you are not even keeping even. He recommended some nasty poison in cat food, that the jackets would take back to the nest and feed to the queen.