[akarlsten]

We had a wasps nest last summer inside the wall under the eaves of our house, some kid from the exterminator's came with a long telescoping rod and puffed some kind of white powder into the opening. He explained that it was something like a slow-acting poison (or maybe like diatomaceous earth) that would cover the drones when they left or arrived at the nest and that it was enough for one of these drones to brush up against the queen to kill her. They swarmed around for a few hours then we never saw them again, so it apparently worked.

This was after attempting to spray the opening with regular wasp spray a few times. Sure, it killed a dozen or so drones each time but never really put a dent in the population.

[exasperaited]

A good spray picking off the very earliest dozen or so wasps in the early spring may actually directly get the queen, who has not always permanently settled in. That point or the next few weeks is an excellent opportunity to add secondary toxins that the workers will carry in, because the nest is so small they will encounter the queen.

Beyond that I guess only completely saturating an internal trunk route through the thing with a tool like that is going to work!