About 2 weeks ago found out at our other house (not being used) had a family of GH under the decks. Only had one hole that was visible, so poured ammonia down it and that did nothing. Got my Remington 552 and started sitting out in the truck a bit away, and over the next 4 days got all of them (Mom, Dad and 2 pups). Only way to fill in the holes is to tear the decks up and don't want to do that. Have read that once they have been used as a nest, its only a matter of time before another one comes back. What can be used to keep them away?