[Old Thomas]

Try Sevin insecticide. I have used it on honey bees and yellow jackets and it knocks them dead overnight. I have used liquid in a sprayer and powder. I had a huge hive in a hollow tree. I put powdered Sevin in a 10 foot long plastic conduit, plugged the end to keep it in with a plastic plug, and stuck the end in the hole. Then I shot compressed air in the other end of the conduit pushing out the plug and blasting a white Sevin cloud into the hole. The next day there was not a single surviving bee, and 2 years later they are still gone. Liquid is easy, but I had to have some fun with a home made powder gun.

 

[BayouRunner]

We get yellow jackets here all too often. Had someone weed eater around my trees for me last weekend. He got stung four times around different trees. About a half a cup of gas instantly knocks out the in ground nests. Takes a few days for the stragglers to go away. The ones in the wall will require a different treatment. Usually the nests are up higher in the wall and the go out through a lower entrance. So when you use wasp spray or something similar it only kills the ones in the immediate area. They are alive and well in the wall. Switch to a dusting powder like suggested above and you will wipe out the nests in a week or so

 

[gkreamer]

You could look for the can at the store that says kills instantly and shoots 20 feet of you go the bang on the wall route. It basically is an instant kill as it just disrupts their nervous system or something. I think we had Spectracide brand, it even killed giant European hornets instantly that used to get angry and run into our floodlight on the corner of our soffit. A direct hit dropped them instantly to the ground- no crawling or anything, the mist slowed then down and killed then on a few seconds. My 25 year old son is still terrified of yellow jackets, wasps and hornets. When he saw the"murder hornets" story last year he added Washington state to the list of places he'll never go to, so now Australia has company!