I had a hornets nest, used tempest powder at night. 2 days later all dead.
I had 2 yellow jackets nests, one inside a sophet, a little blast of tempest at night by each entrance. 24 hours later all dead.
YJ nest in an old stump, night time visit, all done.
This was last weeks problem. Now completely gone.
1) do not use a flashlight with hornets, especially the bald faced ones, they do have "guards" that will follow the light.
2) get a long bulb duster, it does not take much powder to kill a nest. only a few need to get the powder on them to spread it quite well.
3) Make sure you know where the entrance is, when it's dark you don't want to be guessing. First round on the hornets nest I completely missed the entrance and had to go back the next night to finish the job.
Good luck, and do not breath in the powder! This is only advice, I am not a pro, have just taken out a few dozen YJ and hornet nests this way.
If they are high up and you feel you need to use a ladder, call a pro, hard to run on a ladder
If you do not feel safe or are allergic, call a pro.
If you get chased when you try to do this, they will become quite aggressive.
Call a pro if you have any doubts. I know too many people that have learned just how fast/nasty these things can get.
The cans of spray only work if they touch the insect that is to be destroyed.
I was never able to get a whole hornet or YJ nest by using cans of anything.
Do not use tempest where it can get ingested by anything you don't want to eliminate, read the directions.
Good luck in your decision.