I had them build a nest up in the insulation of a mobile home we had back in the 80s. First sign was one stung me on the back of my leg while sitting on the toilet. At the time there was a guy local that would collect ground nests to sell for making anti venom. He wouldn't come for the house nest but said he would remove it if I found him a ground nest. Luckily my neighbor got into a nest of them while building his fence so I had the guy come out and get that and get those suckers out of my home. He raked out 3 or 4 grocery sacks full from under my house.