Mason bees are one of the 40,000+ native species of bees in North America. Their specialty is early spring pollination, especially of fruit trees, which gives them their other name- Orchard bee. They are small, blue-black in color and rarely sting. Mason bees are "solitary bees," so while they nest near one another, they do not form colonies and therefor have little to defend.
These and other native bees will gladly nest in tree cavities, but they are also attracted by mason bee houses that consist of deep holes 5/16th inches in diameter. Katherine and I lined the holes with parchment paper so that the bee cocoons can be removed and stored in the refrigerator over the winter.
I suppose a patient person would just put out the houses and wait for the bees to find them, but that is not one of my traits. I ordered 20 cocoons from Oregon, some of which broke dormancy during shipping, and put the rest in the crisper drawer until today!
Here is the first bee to emerge from the box of cocoons! We have warm weather, flowering trees, and shelter so the rest is up to them. Good luck guys!