The last time we shared our yard with wasps everywhere, I traced them to nests being built in 3 places on the exterior of my neighbour's home, and I also saw them go in under their wood siding. After I let them know, they got the sites treated and the air in my yard was free of wasps, except for of course the occasional one that was flying by.
This time, the detective/surveillance work is more challenging. I was able to track several going into a cracked board under one of my downspouts, so it appears as though they have taken up residence INSIDE the roof of my carport somewhere. I've seen over a dozen going in. We've used the 'bomb' spray before, but since I have an exterminator coming to try and rid my house of carpenter ants I've seen march all the way up my back stairs, across my deck, and into a hole that a cable was once fed through, I'm having that guy treat the wasp site as well.
I am ok with having to share the outdoors with nature, but once nature wants to live in my house, it's war. We've had carpenter ant problems over winter in this home previously, but we did not know of the hole they get in through. We thought the problem was solved when we replaced the deck and shed, but NO. I had a few show up in my kitchen during heavy rain, but they seem to be staying outside for the mostpart. Still, I've had enough years of them showing up inside in November when they are supposed to be dormant, so power-spraying that hole in hopes of hitting the nest in the wall is best.
I still think there must be another wasp site though-there are way too many out there.