I am so excited! I have a bumble bee nest in my yard! As you may have noticed, I have developed a pronounced bumble bee fixation. I read about them. I draw them. I pick up their little dead bodies on walks. ( Have you ever noticed how focusing your attention on something makes that thing pop out at you everywhere? Little furry bodies on the pavement just jump out at me. It may be that they were always there or maybe there are more now.)
My son made a bird house several years ago that birds investigated but never used, perhaps because it has large openings on three sides. Every year chickadees look the place over and add a few bits of grass and moss. I thought I saw a queen investigating it in March. But it is suspended from the overhang that protects the basement door and bumblees like to be closer to the ground. Yesterday my husband asked if there were wasps in there. I went outside and saw two bumble bees fly in the opening. I am in bombus heaven.
I thought about building a nest box as described in several books but they were all discouraging as to the possible success rate. And here the lazy gardener triumphs again. Don't be quick to clean up. Leave things around the garden. Someone will put it to good use.