Scorched earth. The only way to deal with the lil ba_stards. They burrow in and make themselves at home. They invade your property and then get all pis_sy when you tend your own lawn. No I'm not talking about Democrats, I'm talking about ground hornets. Just took out another nest in the front yard this time. Last year it was the back yard. This year it's the front. Lil fuc_ks got me twice today, on my elbow and the knuckle of my ring finger, lil ba_stards. Last time I cut the grass a big somebitch tagged me on my big toe. I thought I was shot in the foot it hurt like hell. Nice red dot swoll up my whole foot for 3 days. Couldn't walk the day after. I got them back tho. Seems the lil ones hatched out and were swarming the nest so I could see the general area this time....hundreds. Seems the young lil ones guarding the hive don't have as bad a sting as the adult that popped me last time. I just filled up my 2 gallon gas can for such an occasion and poured 1 gallon into a pitcher, lined up my shot and drenched a good swath right on the center of the ground swarm. went get the matches and a brown paper bag. Lit the bag and tossed it on. WHOOOOFFFFF Die fu_ck heads. Let that burn a while, continued to cut the lawn. After the fire was out I could see the entrance. Went get the shovel and dug up a good size nest about the size of my fist, buried bout 12 inches down in the hard pack. Hand starting to swell up....$4.38 worth of gas ...neighbors about to call the fire department.....crazy old man slinging dirt and cussing a sorts of expletives at the ground....worth it.

have dealt with this for years. my technique is to get a fifth of liquor glass bottle and fill it with gasoline. find the nest entrance hole and slam the bottle neck down into it. some of them will be flying around and after the bottle gets slammed there will be more. give things a few minutes to settle down as much as they're going to and to let the gas empty out of the bottle and seep down in and around the nest. then quickly remove the bottle. stand back a safe distance and throw a lit torch or rolled up lit newspaper onto the whole. the vapors will burn for some time and voila no more nest. 

  If you chew tobacco you are in luck.  Some freshly chewed (long leaf like Red Man but I guess Skoal or Copenhagen would work as well) placed on the wound will stop the venom and pain almost instantly.  I would not have believed it had I not been stung by some Yellow Jackets and some jaw wide dude comes up to me and says "Hold on kid.  Put this on them spots where ya been hit."  (Or words to that effect.)  The pain went away immediately along with any swelling and dexterity issues. 

I ran over a nest, it was literally with my riding lawnmower. I parked the lawnmower over it with the blade turning for about 5 min.