If you ever need to get rid of hornets, burn them out with a mix of gasoline and styrofoam, it's a poor man's napalm and it burns good and hot. Of course, don't do this in your house, I'm only talking about if it is outside in your yard somewhere.
The best part is that, because of the stickiness of the styrofoam and gasoline, the hornets can't get out and attack you before they are already sticky and on fire. If any are left outside, just burn them with a lighter when they get near you. A note: the fumes are still just as explosive as pure gasoline, stand clear when you drop the match and NEVER pour more on top until you are sure the fire is out.