When the nest is inside the wall, not on it
A nest you can see is a nest we can reach. A colony inside a wall void cannot be sprayed from outside, cannot be taken down, and gets worse if you plug the hole they are using, because a sealed-out colony chews inward and opens into the room instead.
That case has its own method, its own timing, and its own set of mistakes to avoid, so we wrote it up separately: yellow jacket nest in wall removal, including how to find the entry and why the hole has to stay open until we get there.