You may only see a few bees flying in and out of an entry point but there could be thousands of bees inside. Sealing the bees’ entry point will make them look elsewhere for a means of getting out. Often times, they will begin coming in the house because they have no other way to get out. The bees' regular routine is interrupted as well, making for a more difficult removal. They may begin building a nest at a new spot closer to a new exit point. Then there will be two nests to deal with, both the old and the new. One job I did had the bees’ entry point sealed and the bees had been coming in the house for the last two months