Manmade bee nest boxes
We've been fascinated watching bees lay their eggs in bee houses, both homemade and commercial versions.
John just drilled lots of different size holes (between 2 mm and 10 mm) into this assembled hunk of wood, making sure he bought only NON-pressure-treated wood. (Pressure-treated wood is full of toxic chemicals.)
He nailed three 2x4s together and then drilled the holes almost, not completely, all the way through. It's important to have a good drill bit so the insides of the holes are smooth.
He added a roof to keep rain out.
Many different types of bees and wasps use these holes, each choosing the size hole they prefer.
It's been pretty successful, though it can't be cleaned out as easily as commercial ones can be. It's true that nest areas in the wild aren't cleaned out either, but we're trying to provide optimal conditions. Also, I wouldn't think bees would be nesting in such density in a natural setting or even reusing nest sites.
We tied these elderberry stems together for nesting space for bees. I imagine there are other stems that are naturally hollow, but we happened to have some elderberry prunings.
We cut them above a plant node so there would be a natural end at the back so they weren't just a hollow pipe.
Purchased bee houses
Here are some of our bee houses. This photo was taken soon after we installed them, so the wood is still new-looking. They all weather, though, so they blend in pretty well.
We've tried a variety of styles, just to see how each type worked.
Noticed that all of these houses are about 5 inches deep. They need to be this deep since the depth affects the proportion of males and females produced. We try to maximize the number of females since those are the ones that do the pollination work!
Some of these larvae (maybe even most?) overwinter as larvae and leave the next spring.
I haven't kept track enough to know how many batches of young are produced each season.
This type of bee made unusually messy nests, exuding some sticky material—or is it because the nest is plastic?
Although we've enjoyed these houses, I'm beginning to think that, at least in our suburban yard (as opposed to a farm or orchard that needs heavy-duty pollination services), we should focus relatively more on providing as much natural habitat as possible. This eliminates our concern about keeping the bee houses clean. It also avoids concentrating all the larvae in one place, which can make them sitting ducks for predators, such as birds or chipmunks.
I suspect our yard probably has enough places for them to nest even without a lot of houses. We won't get rid of the houses we have, but I'm sure our bare ground and dead logs probably provide enough nesting habitat anyway.
This is one type of bee house we've bought. In the past, I began to favor this type because it's so easy to clean and to get ready for the next year. In other words, I simply removed the straws and put the occupied ones in another container until they emerged, then replaced the house with clean straws.
Of course, one downside was that the straws are pretty pricey considering they're single-use.
I did try to buy beverage-style paper straws, but they're hard to find in any size. The size of the hole didn't really matter since, unlike a farmer, we're not focusing on orchard mason bees, just any native bees, some of which are pretty small. But they just don't seem to make paper straws anymore. In fact, the teen at the register of a restaurant supply store didn't believe there could even be such a thing—"But paper would get wet!" she told me, thinking I was a little confused. Clearly, she couldn't conceive of a time before plastic was invented.
Anyway, I say that I used to prefer these until I spoke with an entomologist who considered these to be a "sink" rather than a "source" for bees in my yard. (In other words, they wouldn't necessarily be able to complete their life cycle, and thus the eggs would be wasted.) Now for the life of me I can't remember her reason, just that whatever her reason, it made sense to me at the time, so maybe this type isn't the best choice.
I like this type of bee house. It's easy to clean because it disassembles, and it has four different hole sizes to accommodate different types of bees.
This photo shows what's going on inside those houses. Notice the different types of cells made by different types of bees and wasps.
Solitary bees fill up a channel with their eggs, provisioning each cell with what their larvae need. Once the channel is filled, that's the end of their parenting responsibility.
They don't stick around to defend a hive, which is the reason these native solitary bees aren't aggressive. Many individuals may nest "together" in one area—in this case, this bee house—but they're aren't organized into a social unit; they just happen to be nesting in proximity to one another.
This is the newest style of beehouse we've bought. It's plastic, which should make it much easier to clean. I'll have to observe it for a while to see if it's as appealing to bees to nest in this plastic.