What are people using for bait? I've killed at least 50 yellowjacket queens this spring but not a single one in a trap. Traps are common commercial traps using their lures and I have also tried the cat food trap shown in the video and have not caught a single yellowjacket.
This is not a new experience but happens every spring and I speculate the queens out this time of year are more interested in finding nest sites than they are in finding food because later in the season the same traps will catch yellow jackets, though not as many as I would like to see.
Also, concerning robbing screens, I'm thinking a person needs to put them on prior to robbing beginning. Seems like once the yellowjackets learn there is something to rob they soon defeat the robbing screens, at least that's been my experience. I'd be interested in hearing other thoughts on this.