If they have swarmed, and I would guess that they have due to your previous efforts, give them a couple of days to settle back down. Sentry guards will fly for a couple of days after a major swarm. Sounds like Yellow Jackets. Go nocturnal and later is better.
Fabric stores sell a mesh fabric, sort of like window screen, called Toole? (sp). 60" wide. Get a couple yards, maybe a couple bucks. I use safety pins to attach 1/2 oz. bass sinkers to weight the net edges to the ground. Sort of a red-neck cast net for bees. Sneak up at night (red lens on headlamp) and drape or throw the netting over the nest. Soft and silent approach, with no heavy steps to send vibrations through the ground. Then you can plot their demise.
Just whacked a ground nest that had hundreds. Gas will bring them out of the nest. I use a 3 gal. pump sprayer with insecticide to hit the escapees that the mesh net catches. Leave the net covering the nest for a couple of days to confirm eradication.
Slight pucker factor putting the net over the nest, but once in place, it gets to be fun. Revenge rage is therapeutic. (Bees only)
"Hello, My name is Bill, and I'm a tackleholic"