Of the 4,000 bee species native to North America, mason bees are among the easiest to raise, while also being gentle and amazing pollinators. Mason bees nest in pre-made holes and hole-nesting bees represent about 25% of the world’s bee species. We can increase mason bee populations by raising them in our backyards and gardens, which is a great way to supplement the stressed honeybee, sustain our future food supply, and provide nesting sites for other native bees, too.
https://thehoneybeeconservancy.org/why-bees/mason-bees/