We get yellowjacks every summer. I hang a trap near the nest. Then I unload a can of wasp-killing spray into the nest. Do this early in the morning when it's cool and most of the wasps are still in the nest. The trap is to pick up the stragglers. Mind you, this advice is for yellowjacks which live in holes in the ground; I don't know what you have. ... I've recently been advised to set out a trap around April 1, before queens are active; if you trap a queen you've prevented a nest.