Native Bee Houses: Encouraging the native bee population

Until this year, I didn't understand the importance of native pollinators. I found the following passage from the National Sustainable Agriculture Information Service:

Native bee box.

'Worldwide, there are an estimated 20,000 species of bees, with approximately 4,000 species native to the United States. The non-native European honey bee (Apis mellifera) is the most important crop pollinator in the United States. However, because of disease and other factors the number of managed honey bee hives in the United States has declined by 50 percent since 1950. During this same period, the amount of crop acreage requiring bee pollination has continued to grow. This makes native pollinators even more important to the future of agriculture.

Native bees provide free pollination services and are often specialized for foraging on particular flowers, such as squash, berries or orchard crops. This specialization results in more efficient pollination and the production of larger and more abundant fruit from certain crops. The pollination done by native bees contributes an estimated $3 billion worth of crop production annually to the U.S. economy.'

   

Wow! Native pollinators are really important, and unfortunately in decline. Last spring, I decided to try to encourage them at my home.  Kate at Living the Frugal Life recently posted about native bee boxes.  She includes links to the Xerces society that include a PDF about native bees and how to make habitats for them. One method is native bee boxes (which I made). There are also bumble bee houses, which I'd like to make sometime too.

You can make native bee boxes out of thick pieces of untreated lumber.  I happened to have some 4x4 posts, so I used that.  I cut 6 of them with a miter saw so that they were roughly 8" tall, and the top had a 30 degree angle.

Blocks cut to become native bee boxes.

Next, I drilled holes in them.  You can do this methodically, but I chose to put the holes in randomly.  I used drill bits ranging in size from 3/16" to 3/8" and I drilled the holes to about 3.5" deep.  Different bees prefer different sizes of holes, so I thought a combination of sizes would have the most success.

Native bee box with holes ranging from 3/16 to 3/8".

After drilling the holes, I attached a roof to the angled end.  I just used a piece of wood that was lying around, cut it so that it had a 1-2" overhang, and I attached it with one screw.  The roof will help keep the nests dry in rain.

Native bee box, ready to install.

At this point it is ready to install--one of my easier projects!  Apparently the bees like to have the holes face the morning sun, so I positioned them around the garden facing the south east.  I attached them to the porch and trellises with a screw through the top of the roof in early spring.

Native bee house with a resident!

Within a week, a few of the holes in the house looked like they had been plugged up, which seemed curious to me.  I did a little bit of research and found out that many solitary bees make a nest in a cavity, lay an egg, and then seal off the entrance.  Later, the baby bee hatches, eats nectar left by its mommy bee, and then emerges from the sealed cavity.  How cool is that?

I think the bees make an excellent addition to our garden. :)  We are helping the environment, encouraging the declining population of native pollinators, AND providing our vegetable garden with pollinators.  That sounds like a win-win for everyone involved!