My Dear Friends,
The pictures helped tremendously! Those are what I was referring to as yellowjackets - wasps are not only the general class of stinging insects, but more specifically the paper wasps in my normal vernacular. Terminology and usage must differ a bit on this side of the pond. My bad.
I will attest that the one endearing quality of this variety of wasps is that they are amazingly stupid. Very aggressive, yes, but dumb as a rock. I have walked up to within two feet of the entrance to an underground nest in broad daylight, wasps coming and going in droves, and poured petrol down the entrance hole. Problem solved instantly.
As an aside, I had been running a string trimmer over that exact spot only ten minutes prior and had no clue they were there at the time I am certain that is what annoyed them to allow me to see the swarm later, but to this day I am not quite sure how I avoided getting eaten alive at the time - by all rights they should have absolutely worn me out before I could reach the relative safety of the house.
Interestingly, while recently building a deck on the side of my house I needed to remove part of a carport - when doing so I uncovered a beautiful wasps' nest about half a meter long. I was very glad it was abandoned...
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Hannibal