We had a couple bad infestations here over the years. A few years back they had entered around a very small gap between the roof and the chimney, unknown to us. The kids kept saying they heard a buzzing in the ceiling above their room, but we could never hear it.. until it got louder over a period of weeks. Then we saw a few buzzing around the roof right above there, put two and two together... and decided enough was enough. Got out on the roof and dumped about four cans of big ol' nasty bug-be-gone through that crack, waited a day or two, then pulled down a 4' x 6' section of the drywall. They had built a nest in between the 2x12 rafters that was 12" thick, 2' wide, and almost 4' long.
Fast forward another couple years... found a nest about half again as big as the one pictured in the grill in the OP in an empty wood half-barrel that I had tossed some Christmas tree branch trimmings the winter before. Couldn't see the next below the boughs in the barrel, but noticed a lot of hornet activity. AWFUL. Made an ersatz bee suit out of raingear, snorkeling gear, mosquito netting, and big oven mitts and went to town. Same year... was mowing the back 40 (ok, the back yard, but it's big and surround by woods) with a push mower and got stung in one spot of the lawn. Thought nothing of it...figured just an isolated event.. went around the lawn one more time, and this time when I got to the same spot I got swarmed. Ground bees. Ran as fast as I could towards the creek in the back and was ready to jump in, but they had stayed by their nest... and swarmed the mower. Fortunately, I had 100 feet of garden hose. Kept a strong spray up, retook the hill (I mean mower), finished the rest of the lawn but stayed away from their burrows (they had found a groundhog den). Took THREE different applications, over three days, of serious bug spray to get rid of them.
Last summer was hornet and wasp free, relatively. WIsh me luck this summer.