Mason bees are just one of the 4,000 species of bees native to the United States. They don’t live in hives like honeybees, but instead are solitary bees and make nests in hollow stems or holes in wood. In my last post, I talked about how nesting sites are one of the key elements to a pollinator garden. It’s super easy to welcoming these native bees to your garden by making a mason bee nest!
There are 135 species of mason bees in North America, and 95 of those in California. Most of them are active from March into June. They range in color and size, but are often a dark metallic blue and have dark hairs on their face. In the native environment, they will nest in pre-existing holes in wood or hollow reeds. In the garden, they will easily occupy a man-made nest. I don’t have a great picture of a mason bee, so instead, I’ll share this awesome capture from my Instagram friend Resilience Design.
Make Your Own Mason Bee Nest:
Mason bees will nest in either a cavity nesting site or in a stem bundle nesting site. You can easily make one or the other, or you can combine them. That’s what I did, and made a ‘Mason Bee Hotel’ using reclaimed materials.
Create stem bundles:
The first thing I did for my mason bee nest project was forage for plant material that are hollow. Bamboo is an easy one to come by, and I had found some running bamboo that had escaped from a neighbor and spread into a local park. Bamboo is also great because it grows in segments, and if you cut the stalk at the nodes, you have a closed end. Mason bees don’t want a stem that is totally hollow, they want a backing to the hole. Other plant materials to consider are raspberry canes, teasel, or Arundo (the giant invasive reed found along rivers).
Cut your stems into lengths of 6-8″. If your stems don’t have a solid back, you might be able to fold them over, or you can place in a container with a back. You can also purchase paper tubes and put them in a fancy holder for less rustic appearance, or you can mix them in with your other stems (which is what I did).
Create cavity nests:
Next, I worked on creating cavity nests. I used a birch branch (also foraged from the park) but you could also use scrap lumber. Make sure to use preservative-free wood! Pine and redwood are great.
Important dimensions to know:
Mason bees prefer cavities made from holes drilled between 3/16 and 3/8” in diameter, at ¾” intervals. Holes should be at least 5” deep, but 8” or more is better.
I cut my branch into sections about 7″ long, and used a variety of drill bit sizes. I’m not strong enough to operate the drill with one hand, so found it easiest to hold the branch section between my feet. Don’t tell my junior high woodshop teacher. Pretty sure this breaks all the safety rules. But I like to live on the edge.
Different size holes will attract different species, and they are fine to cohabitate the same block. The holes should be closed at the back, so don’t drill all the way through your wood. I had all intentions of having holes 6″ deep, but I didn’t have long enough drill bits. I used what I had, and hopefully the mason bees will find something suitable in the bee hotel I made them. Bees also prefer a smooth surface, so you can enter a paper straw into a drilled hole or drill perpendicular to the wood’s grain for a smoother surface.
Create a box for your mason bee nest materials:
Now that you’ve got your stem bundles and your cavity nests, we need something to hold it all together. I made a super simple and janky wood box from a scrap fence board. Because I had backs to all of my materials, I left the back of my box open, but if you are using completely hollow stems or straws, add a back to your box.
I simply cut 4 sections of wood, with one being slightly longer than the others to create a roof overhang to keep out rain. Then, I screwed them together. A prime specimen of fine carpentry, it’s mostly square. And if you look closely at this awful quality photo, you’ll notice a Stella paw print. That’s 4.5′ up the side of my shed. She’s trying to learn to climb walls to get the squirrels. No success (yet).
You’ll also need to have a way to mount the nest to a wall (more on location in just a sec.) This could be another scrap bit of wood, it could be one side of the box cut larger to screw through, a wire hanger, or a metal bracket.
I really didn’t want to go to the store, so I rummaged through my miscellaneous hardware box to find something that would work. I used a metal faceplate from a door knob. Classy, I know.
Mount and fill your mason bee nest:
Now, it’s time to put up the nest! No one likes to lay eggs or hatch on swinging craziness, so you’ll want to place your nest on a firm support, like a post or a wall. They should be in a sunny location, but avoid direct afternoon sun in hot climates. You don’t want developing brood to cook.
I mounted mine on my back fence, facing south. It’s in the corner of the yard and gets morning sun, but afternoon shade. Fill with your stem bundles and cavity nests, and you’re all done!
Now, I just need to wait for the bees to find it!
Important to Note:
My mason bee nest is made from completely biodegradable materials. I didn’t paint anything, and I used soft woods. This will likely start to rot and break down in a few years, and THAT’S GOOD! Just like a natural nesting spot in the wild, this isn’t meant to be a permanent structure. In fact, it’s a good idea to replace your nests every few years, to avoid the build up of diseases.