Getting Rid of Ground Wasps

[Treeflea24]

Here was a fun one that I dealt with a few weeks ago:



This is a yellow jacket nest that was built inside of my home HVAC. Its about the size of a loaf of bread. They came in through the fresh air intake, were able to sneak around a butterfly type damper, and setup shop about 2' into the house. Thats a 6" ID pipe. They never seemed to go exploring further downstream in the cold air return circuit, or at least I havent seen any evidence of that. 
Gas, explosives, and the other fun methods werent options here, so it was Sevin dust. But even at that I couldnt just pump it into the ductwork. I was able to collapse and pinch the pipe downstream of the nest, disconnect it from the circuit without filling the basement with stinging insects, then they got dusted from the entrance using an automotive turkey baster.
The mesh at the intake cover was ~3/8". It is now covered in 1/8" hardware cloth.
Wife was freaking out at all stages of this process - taping off floor registers and cold air return vents, making arrangements for where to sleep if/when our home was overrun with hornets...