
The house design was inspired by some links I came across:
Nests for Native Bees - Invertebrate Conservation Fact Sheet
USDA Natural Resources Conservation Service - Backyard Wildlife Habitat Tips
It simply involves drilling some holes of variable diameter and depth into wood. Since we have lots of dead birch stumps lying around, I thought I'd give it a try.
I was surprised to recently learn that most native bees do not form hives but live a primarily solitary life.
I will be keeping an eye on these homes to see what eventually emerges, though I may easily miss that event. Not sure if they are actually bee nests, or some other insect who prefers this convenient shelter in the dead paper birch stump.

I am at a loss to even venture a guess, I'm not even sure if I can assure our concerned daughter that it doesn't bite. We have found 3 or 4 over the past few weeks, usually alone and somewhat docile but moving. Usually crawling slowly across the floor, the last guy attempted to fly but could not quite leave the ground (see action shot below).