Pollinators are in trouble. Colony collapse disorder has devastated bee populations. Our national love affair with pesticides and insecticides has been a veritable holocaust for beneficial insects. As a homeowner, part-time gardener, and all-around concerned person I felt it was my responsibility, perhaps duty, to build a habitat that was inviting to these insects that do so much for us humans.
The easiest thing that people can do to help out is to stop indiscriminately applying chemicals to our landscape. Just because your lawn may be inhabited by ants and grubs is not license to conduct chemical warfare. As a matter of principle, we should cease applying chemicals on our landscapes entirely because it is so wasteful.
Next, you can create inviting landscapes through the use of desirable plants. I am a sucker for butterfly bushes and other showy perennials that butterflies and bees seem to love. These plants tend to be drought tolerant and suited for my eastern Iowa climate, so all the better.
Lastly, I decided to create some homes for mason bees. Mason bee is a generic name for a genus of bees (Osmia) that contains hundreds of different species. In North America, according to Wikipedia, there are over 130 species. Mason bees, unlike the more well-known European honeybee, are solitary and do not sting unless physically provoked.
One way to encourage mason bees to inhabit your yard is to make a “house” for these garden helpers. You can search the internet and find hundreds of variations of mason bee house construction from painfully simple to bizarrely extravagant. I am going to hew closer to the simple side of the spectrum with my construction because I prefer that aesthetic in my garden.
I started with a scavenged piece of 4×4 dimensional “white” wood lumber. One key thing to remember when constructing your mason bee house is to avoid treated lumber at all costs. You do not want to create an environment that actively kills the mason bees seeking to build a home in your yard. I suppose you could use cedar or some other fancier wood to construct a house, but I liked the idea of using a scrap piece of wood. My guess is that this was originally spruce or fir because of the smell when cutting the blocks and the lack of sap, which seems to be so prevalent on pine lumber.
I cut blocks that were approximately 8” tall and had a 10 degree slope cut on one end for the attachment of a board to act as a protective overhang:
Again, I utilized a scrap piece of 1×6 pine dimensional lumber to construct the overhangs. I simply nailed the overhang to the block with a trio of small nails.
Somewhere in my research, please let me know if anyone has a source, I read that a 5/16” hole is the perfect diameter for mason bees. I do not know if this is true, but I am going to roll with the idea this time and see what happens. Lacking a drill press, it took some time to drill all of the holes necessary for the house.
I was going to have more holes per block. However, I quickly discovered that it would have weakened the wood block considerable. So, I cut the number of holes in half and staggered them across the face of the block to create the environment for my soon-to-be garden friends.
Scavenging through my parts box and a friends bin of leftover plumbing supplies from many remodels of pre-World War II houses in eastern Iowa produced the perfect mounting system. I kind of wanted a more industrial look to the houses than a simple wood stake would provide. A pipe flange screwed to the bottom of the mason bee house and a two foot long piece of threaded black pipe were an ideal solution:
My hope is that over time the pipe rusts to a nice patina and I can easily reuse the pipe/flange combo by simply unscrewing it from the bottom of the house.
Amidst the butterfly bushes on my west facing garden bed these little houses look perfectly at home: