I enjoy evil folk remedies the best. The time is past when we could use R22 on them. Just froze the little jerks. And I have little faith in any commercial/homeowner grade product the EPA will allow them to market.
If you have a safe shooting backstop, you can just shoot the things a few times. Sure, you're 100 yards away, and they have no idea where the long range artillery is coming from, only their house is being ripped apart.
For the ones in the ground, you need to use a small bungie cord on your modern lawn mower to keep the blade turning. They do mulch well. You won't get them all, some stay in the ground. At home, I just used some topsoil in the depression where they went in. Must have been a small nest because they didn't come back out again.
About 25 years ago I was attacked by a swam on some property a club I belong to owns. They were all over my back before I even realized it. A friend saw it and pulled me away and smacked as many as he could. They put me in "detention", up in the shade, no beer, and a watcher to make sure I didn't go into shock or have an allergic reaction. The watcher was given a "magic marker" of a commercial product called "Sting Foe". Its also available in swabs, and the local phone and electric company issues it to their pole crews.
Anyway, my probably illegal retaliation was to mix up a 5 gallon jug of contaminated gasoline and about a gallon of drained 90w gear oil. Then at dark I took it over to where I'd been cutting and found their hole. I just began pouring. And pouring, and pouring. All 6 gallons of the sticky smelly mix, down the main entrance to their castle. Any that got the stuff on them couldn't fly. The fuel was killing them, and the heavyweight gearoil was weighting them down. I enjoyed their suffering, too. Then I went back to my jeep, located my pengun and a flare, and fired it at the hole from a safe distance. It went "whoomp" and up went the flames. Then the stuff down in the bowels of the earth started to burn and eject the evil little critters out, all a flame. Like a roman candle, toasty little stinging critters. Snap, crackle, and pop. They had side entrances, too. Didn't matter, those were a fire also. What was the saying? Burn baby, burn.
You think we have a problem, linemen run into hidden nests all the time. The product is green and just a little sticky as it dries. Main ingredient is alcohol to sterilize the wound (thats what a sting is.) It also has a novocane or zylocane additive to stop the pain and numb the area, and some menthol, like in cigarettes to cool the spot. Good stuff. All those who work outdoors should have some of it. I keep some in my first aid kit in both jeeps. Also consider some Benedryl. It seems to be what my doctor recommends to prevent a reaction to the sting. One of my son's is allergic, last time he got stung the doctor said give him twice the normal dosage, then watch him for 4 hours. Boy is that boring.