What are they doing?
I have a wooden birdhouse about 2 feet long that looks like an old red barn. I set it on my deck bench every summer as a decoration. It has 5 holes in the front. For the past three summers we've noticed bees move in. They don't bother us so I let them stay. They look like bumble bees, but they are smaller. We see one going in and out occasionally, and if we bump it they buzz. But none come out or anything.
Today, there are three or four sitting outside the hole buzzing their wings. The whole thing is humming. Every once in a while one will crawl inside, and then back out and stop with the others to buzz it's wings. Another bee came and flew into a different hole and I noticed it had bright red on it's hind legs. In a couple of minutes it flew out. No one has bumped it or bothered them today that I know of unless the cat did.
Any ideas what kind they are and what they are doing?