How to create a shelter that attracts native pollinators to your yard
Last winter my wife sent me a link to an article on insekthotels (“insect hotels”) from a popular German nature website. If you’re not familiar with these (don’t feel bad, I wasn’t either), they’re basically the same as a birdhouse except for insects instead of birds. And, like a birdhouse, there’s all kinds of design options based on the insects you’re trying to attract.
The insect hotels in the article were huge and elaborate pieces of art, built like Alpine chateaus, castles and sod-covered hobbit houses. Nice to look at, but nothing I was going to imitate (too fancy and I don’t do fancy), but they did look cool, so I decided to learn more about them.
What Lives Here?
The first thing I learned was you need to know what kind of insects live around you. If you don’t, you might end up spending a whole bunch of time building nests for bugs that live only in Northern Europe even though your hotel is in Southern California.
After schooling myself on the locals who might be guests for my hotel, I decided that most of the bugs have plenty of nesting space in the surrounding area. Native bees, however, are having trouble, so I decided to make my hotel bee-centric (though not bee-exclusive — all insects are welcome).
Building a Bee Hotel for the Western United States
The West coast of North America as well as Arizona, New Mexico and the northern states of Mexico are home to many varieties of native bees — up to 1,600 distinct species by some estimates. Most of these bees are solitary or live in small colonies. There is no queen, no massive hive, or stinging like there is with the European honey bee.
It’s no surprise that bees living in the arid climate of the west are for the most part ground-dwellers and lay their eggs in burrows or tunnels. A few, however, nest in wood, which is much harder to come by. Here in the bottom left hand corner of America, there are three species we see on a regular basis:
Mason bee (Osmia Californica)
These guys are a smaller bee — about the size of a honey bee — but usually darker without the pronounced yellow stripes. Solitary and non-aggressive, they’re called mason bees because they use mud to seal the cocoon and some pollen for food in small cavities.
California Carpenter Bee (Xylocopa californica)
This is the big, black shiny show moving bee we were all scared of as kids. Despite it’s badass looks, it’s actually very docile and a great pollinator because of the sheer amount of pollen it can carry. (Seriously. If a honey bee is a hatchback car, a carpenter bee is more like a 30-foot semi tractor-trailer.) It’s known as the carpenter bee because it hollows out old and rotting wood in which to lay its eggs.
Leafcutter bee, (Megachilidae ssp.)
A cousin of the mason bee, this one likes to line its nesting tubes with pieces of leaf it cuts (thus the name). It carries its pollen on the underside of its abdomen instead of the legs like a honeybee. To pick up pollen it uses a swishy side-to-side motion sort of like a Swiffer Sweeper, so it’s really good at spreading the pollen around. (It’s probably a great way to scratch and itch too.)
Designing the Bee Hotel
Since these native bees are all wood nesters I decided to skip using bricks and pottery like other insect hotels and use only wood and/or reeds for the “rooms” in the hotel. Otherwise, I stuck pretty much to the suggested rules — at least 3 feet from the ground, 9 to 12 inches deep, and a variety of woods and nesting cavity sizes.
For the construction materials I didn’t want to buy anything, so I used leftover wood reclaimed from some other projects. The hotel frame was made from some pressure treated 2x4s from an old landscaping project and some 1×10 pine boards salvaged from a built in bookcase I’d recently torn out. The wood and reed “rooms” would be made from logs from the wood pile and dried arundo, which is an invasive cane from the Mediterranean that grows in the creek bottom nearby.
My original design was a narrow building, 6 feet tall with an A-frame roof like I’d seen in the German article, but it turned out to be highly unstable, so I switched to a shed roof made from some corrugated steel panel that hung off the back far enough to act as a counter balance as well as give some shade and rain cover to the back of the hotel. After that, it was pretty much just a matter of cutting the wood and screwing and gluing the hotel together.
Building the Bee Hotel
For the upper portion of the hotel, I built a box that was 36-in x 20½-in x 9½-in (basically two shelf boards cut to 36 inches and placed side-by-side) and used the remainder of my shelving to subdivide the box into two large and three small “rooms”.
Then I took my four 6-foot PT 2x4s and screwed them on to the box to make the legs.
For the roof, I used some scrap 2×4 to create the frame and mounted a 36-inch piece of leftover corrugated steel panel to it. Then I popped that and the top of the hotel and secured it.
After I had the roof mounted, I attached a piece of cedar fence board to the front to finish off the upper compartments and painted the whole thing with some barn red primer.
Once the paint dried I carried the hotel down to the lower yard and stood it up in an area that I’m turning into a “poultry-friendly” Mediterranean garden (which is more difficult than it sounds).
Now that it was stood up, I drilled ½-inch,5/8-inch and ¾-inch holes in a variety of wood logs — oak for the critters that like the hardwoods, and pine and agave stalk, for those that like burrowing in the soft wood. Then I cut up Arundo cane for the tube dwellers, and drilled some redwood blocks for the smaller bees that like orderly condo living.
Oh, and I topped it all off with the sign “Hotel de Sage” to let everyone know it was open for business.
Occupying the Bee Hotel
I built the bee hotel in spring because I knew the bees wouldn’t be looking for nesting sites until late summer and early fall. Since my potential guests are all fans of old and rotting wood, I figured 4-6 months would ensure that the “new bee hotel” smell would be gone by then.
Over the months I’ve inspected the hotel now and again to see who’s taken up residence. I spotted a couple of tunnel spiders (love those reeds), a mud wasp, and a little fence lizard, but never any native bees. From my reading, this was normal. Many people said they didn’t get any bees even years later, so I wasn’t too surprised to not see any myself (It’s not like there’s a Yelp for bees to find hotels near them).
But then yesterday, I went down to the hotel to grab a couple of quick photos for this post, when I spotted this.
Yep, that’s a carpenter bee who’s making herself at home in an agave log (¾-inch hole – they’re big)!
Closer inspection revealed that at least three logs are occupied (as evidenced by the sawdust being kicked out of the holes), but I’m hoping by the time fall rolls around a lot more of the spots will be taken as well. But even if they aren’t, I’m still really happy with the success of this bee hotel in its first year of operation.
If you’ve ever thought about building one of these for your own native bees, I highly recommend it. There’s nothing quite as satisfying as knowing that all kinds of nature finds home in your garden.