We had a fair size colony, counted close to 80, then it got too dark to count the rest. Watched for their exit spot. Luckily we had only one entrance/exit for it being such an old house. We put up a bat house in the flight path, but a bit lower. In the fall, when we stopped seeing them, we sealed up the entrance, and removed all the guano. Complete haz-mat suit, recommended full face mask, filters. Got an old shop vac, swept and shoveled into bags, some into the garden, the rest a friend took for his gardens. Next year we had no bats. Second year, we moved the bat house further from the old area, and they moved into the bat house. It was good to see them back, we were afraid we had chased them off completely. There are companies that will remove them, but its pricey. We just read everything we could, and were lucky enough to do it right.