> Still, nothing - not even ants - can ruin a good picnic the way wasps can.
Try hornets.
Possibly more effective; set a tank type vacuum sweeper there, with the end of the hose near the wasp nest. When they come in to land or they takeoff, they are sucked into the hose. When you’ve captured them all, a few puffs of bee killer into the hose kills them, and you dump them into the trash.
If you only work at night, seal all but one entry/ exit point. Shove a peice of garden hose into the opened and pour a quarter cup of gas in the opening.
Plug up that last hole. Bugs dead in 2 minutes.
Keyhopper, beekeeper at large