After spending some time browsing for a Mason Bee house this is the best found. I have ordered one, since I desire to go into mason bee production. The price is reasonable, and the construction appears to be well thought out. This is my first effort in producing bees. A lot of reading separating the essence from the chaff.
https://crownbees.glopal.com/en-CA/p-25/spring-reusable-wood-trays-for-mason-bees-48-hole.html?utm_source=crownbees.com&utm_medium=pr&utm_campaign=en_US
Mason bee home.
