Mason Bees, Take #2

Last year I bought 20 mason bee cocoons and built the enclosure below. The bees almost all emerged and we saw some brief activity with them building. But pretty quickly it stopped. Still I was hopeful that in the fall once any larvae had matured into cocooned bees and gone dormant for the winter that I would open up the house and find a few cocoons. The holes clearly weren’t full though. Turns out I didn’t get any babies at all.
I took the house apart, soaked and really scrubbed it with a bleach solution. There were a lot of mites in it. The house had gotten pretty moist during the winter and some mildew developed. At the back of two of the channels there were signs of a bit of building, but nothing more. The last few months I’ve had the whole thing clamped up in the shop so it could dry out
At my grandpa’s house he showed me an old wood pile where mason bees were nesting in the grooves of some old tongue and groove flooring scraps. That makes me think they’re not super picky. Still my wood’s warped a bit and cracked over the winter, so I’ve added a bit to the house to make sure things look sealed up dark and safe inside to them.
And I put a fresh coat of “pi” paint as a nest site identifier. Last fall it was interesting to watch the bees hovering in front of that up and down and back and forth and then diving in the same slot over and over again.
This year I’ve bought tubes instead of cocoons. They’re cheaper and give more bees (20 tubes of multiple cocoons vs 20 cocoons). Maybe I’ll have more luck this time around.
The berry bushes are starting to wake up after the winter and look set to produce a lot of fruit. I’ve been seeing a few honey and bumble bees already and haven’t had trouble with pollination. But it can’t hurt to encourage a good local mason bee population.