Here’s a site that recommends soaking their nests with lemon scented ammonia, then hitting the survivors with a tennis racket. That sounds like the most fun.
If you can get your car close to the hole, get a piece of the aluminum dryer vent hose. Slip the hose over the exhaust pipe and prop the other end over the hole. Best done after dark as wasps/hornets are sight flyers and in the nest by dark. Cooler evenings are even better. Let the car run for a couple of hours over the nest, carbon monoxide is heavier than air and will sink down the hole. Dad and I did that years ago with a burrowing yellow jacket nest. Those buggers are nasty in spades.
Now if you are a sadistic bas#$^%, get a torch with a rose bud tip. Set up a short ways away from the nest. Light the torch, hole the tip a couple inches back from the hole, then pound the ground. Wings only last a split second in 6K degree flames. Be careful though, they pile up quick. 
Bob Cope said: Let the car run for a couple of hours over the nest…
Are you nuts? Gasoline costs more than bug spray.
edited to add: How would this method work with a hybrid or an electric vehicle?
Joe, I really hope you are the only person to ask that question.
Bob said
“Joe, I really hope you are the only person to ask that question.”
Oh come on Bob , it was a fair question , he just wanted to point out that you could electrocute them at the same time as gassing them and still be a green nutter into the bargain .
Mike
…winking…
Bob Cope said:
Joe, I really hope you are the only person to ask that question.
Bob,
It’s a good thing you were just hoping. It being Monday some will have an early go/start at their usual quota of silly contributions.
BTW regarding the hornet problem I’d go with the combo approach, drown them first at night and whatever is left gets the spray treatment as they exit the nest.
Hans , you’re at it again . Stoppit . Or try lightening up and join the fun instead of trying to be a bloody stereotype .
Mike
HJ,
You have ABSOLUTELY no sense of humor, do you? Lighten up. It was meant to be funny, not silly. 
Bob Cope said:
Joe, I really hope you are the only person to ask that question.
I hope I’m the only one to ask that question too, as I see you have no sense of humor either!
Joe , take a look at the post Hans made in the “Website” section .
If he has his way , we’ll all be filling in forms and writing disciplined reports .
You vill not hev fun .
Mike
Joe Zullo said:
HJ,
You have ABSOLUTELY no sense of humor, do you? Lighten up. It was meant to be funny, not silly.
You just wish I had no humour 
I purposely hold back with my very acerbic humour since a lot of people have great difficulty dealing with it, without complaining to Bob. Bob is busy enough without having to wet nurse a bunch of cry babies.
Which is precisely the reason I ignore some people completely and poke only mild fun at others.
PS Note to David M: I’m presently sitting on my b… editing the first segment of the VIA # 2 trip. 
Joe, I have a good sense of humor. However I find NO HUMOR in someones issues with a critter that, for those with allergies, can be DEADLY! I find it very disheartening that there are those who must find humor at the expense of others, especially those trying to assist another.
Mike, I fully understand the ‘Limey’ dry humor. My lineage goes to Stoke on Trent. I grew up with my grandfather’s humor. Again I find no humor at others expense.
For the most part, I follow HJ’s philosophy of ignoring the obnoxious ones. My time is far more valuable that getting into a battle of wits with unarmed people. So read this as you will…
Hans-Joerg Mueller said:
Joe Zullo said:
HJ,
You have ABSOLUTELY no sense of humor, do you? Lighten up. It was meant to be funny, not silly.
You just wish I had no humour
Which is precisely the reason I ignore some people completely and poke only mild fun at others.
PS Note to David M: I’m presently sitting on my b… editing the first segment of the VIA # 2 trip.
HJ, Not having humor! Nah!
Bob , the obnoxious things about Hans are
a) he cannot be wrong
b) he cannot be wrong
c) he cannot be wrong .
Other things are humour is fun when shared , he does not understand enough about humour to share in it . His so called acerbic wit (only half correct ) , gawd what a pompous bloody thing to say . He wouldn’t know a cerbic if it bit his bum , though he appears to know everything else .
Hans , people go to Bob because you are so bloody arrogant that you will not listen to reasoned argument , and further , you have caused other people who did not agree with you to leave the site , so some go to Bob in desperation .
Your other problem is cowardice . You rarely start in on anyone , but gleefully join in when the target is outnumbered , but what can we expect from someone who on his own admission takes pride in the fact that he fled his homeland to avoid doing military service .
So do not expect any sympathy from me , mate . Just try to behave like the citizens of your adopted country and stop trying liebensraum .
Mike , who you will note does not hide behind semantics and innuendo (Hans is too clever to use his
name because he can then say , as he frequently does , he did not mean Mr A , or worse , thus leaving some poor innocent Mr B wondering if he is guilty of some sin )
ps I note with interest that HJ has come out as a cook .(See Other Hobbies)
I bet his kitchen has a set square , compasses , and other precision hand tools to ensure people
get a square meal
Finally , beware if you receive an email in in bad english asking about HJ and
saying what a ratbag he is and even send unflattering pics of HJ . Do not fall for it . It may not be who he is purported to be .
Thank you Larry.
Are you guys trying to argue my wasps to death?
Back to the issue…
I have read that pouring cheap vodka/alcohol down the hole works as good as gasoline. I cannot use gasoline as the nest in dead center of my front yard planting, and gasoline creates a good sized dead zone around the hole. I will check tonight to see if the mound of Diatomatious Earth has had any impact.
Why do so many posts have to descend onto crud like this?
Anyway, my cousin was hospitalized when she ran a lawn mower over a nest of them buggers. When I had them in my yard, I burned them out. My neighbor had given me a can of wasp spray, and it really pissed them buggers off when I sprayed them with it. Filling the hole with water didn’t seam to work very well neither. But pouring lamp oil down the hole, and setting it alight, did the trick.
Vic Smith said:
Are you guys trying to argue my wasps to death?
What? I thought they were hornets?!
Back East (in Toronto) the parking ticket yokels are referred to as “Green Hornets”(it’s the uniforms).
So are your hornets green? If so, send them off to Toronto, Ont Canada and address to Rob Ford at City Hall.