Particularly useful in orchards, mason bees (also called blue orchard bees) can visit hundreds of flowers per day. They don’t make honey, but they collect pollen for nest holes where they lay eggs, and then plug the holes with mud. They look like small blue-black flies, and they rarely sting.
The bee larvae and cocoons spend the winter in the nesting holes, and then hatch in the spring about the same time as fruit trees blossom.
Mason bees live about two months, generally staying within a radius of about 100 yards of where they hatched. Mason bees use holes in tree bark, fence posts, construction wood, or any other opening a little bigger than their bodies for their nests.
Making a mason bee box
The bees managed to sneak into our garage and fill several of the holes in the shelving pegboards. While nesting blocks can be purchased commercially from garden supply companies (so can the bees), it’s easy to make bee boxes of your own.
Use 2-by-4 planks of untreated lumber, ideally placed near the fruit trees that need pollinating. From our experience, the bees prefer quarter-inch diameter holes almost as deep as the wood is thick (just under 1-3/4 inches). Commercial nest blocks use straws in nesting holes, but we found the bees wouldn’t use them here.
After you get your nesting block up, watching the bees fill the holes with eggs, pollen, and mud is great entertainment!
You can find mason bees and mason bee houses on our Organic Pest Control and Garden Products Finder – MOTHER