We had a visitor set up shop in our shed... No stings, but not too cool!
Seemingly out of the blue... And one day, it was there. Oddly, we didn't notice anything flying around, or any attempt by the hornets to defend their little nest
Saturated I went and got some Black Flag spray for hornets, and doused their nest with it. No adults inside, but there were about a dozen or so early-stage pupae in there...