Pollinators are important for gardeners because without pollination there would be no fruit. Several years ago, I built a “bee block” from a 4X4 with holes in it to serve as a home for these little pollinators after watching them enter holes in the brick wall left by anchor screws used in the old greenhouse.
They are very busy this year building their nests and fun to watch. They are very docile, the males can’t sting and the females won’t unless you try and grab them. I’m not sure what variety of mason bee they are, they are about the size of a housefly and disappear into their holes quickly so it’s hard to get a good look at them to see the coloring. This group seems not to have a lot of coloring and be mostly black.