Offering homes for bees
People often think of bee homes as the hive boxes provided by beekeepers for their honey bees. In their original habitats (honey bees are not native to North America), they nested in tree hollows, often very high up off the ground (away from predators). Bumble bees (the other social bees, with queens and workers) favor old mouse burrows or other cavities in the ground.
The majority of the other 25,000 or so bee species are solitary, nesting in the ground, in tunnels inside wood, or in dried hollow stems (some desert bees even burrow into sandstone!) Even though these bees are solitary (each female provisioning a nest for her own offspring), they often nest in “communities” that can number into the thousands. If you see a number of miniature volcano-type mounds in your soil, you may have stumbled on a group of ground-dwelling mining or sweat bees!
For ground-nesting bees, the best thing you can do is ensure there are bare patches of soil in sunny locations. Not everyone appreciates how this may look in their garden, but you’ll be well-rewarded when a community of ground-nesting bees move in! If you want to make a real project of it, here are some (PDF) instructions on building a dedicated ground-nesting “bee bank”.
Building “bee hotels”
You may have seen mason bee boxes or “bee hotels” sold in stores. More attention is being focused on mason bees, because they are excellent orchard pollinators, and farmers see them as a potential fallback pollinator to rented honey bee hives. Mason bees (also called orchard bees) like to nest in holes in wood, and seal their nests with mud. They will also nest in tubes… all they really need are the right sized nesting tunnels, a close source of food, and a supply of mud (don’t forget to ensure there’s mud for them!)
Wood nesting blocks
If you buy or build your own “bee hotel”, there are a number of designs to choose from. Try drilling nesting holes between 3/32″ and 3/8″ in diameter into a piece of wood (any type of treatment/preservative-free wood besides cedar). For holes less than 1/4″, the length should be around 3″-4″ deep. For holes 1/4″ or larger, 5″-6″ deep is best (because it changes the sex ratio depending on how long the tunnel is!) For mason bees, drill holes of 5/16″ in diameter, with a length of around 6″ (leaf-cutter bees will use these holes too, later in the season).
New bees will emerge the following year (depending on the bee, sometime between early spring to early summer). One thing to watch out for is the ability to manage these nests… it really helps to be able to open them up and clean each of the nesting cavities so as to avoid the spread of parasites (which love bee boxes too!) If you do drill holes into wood, be sure to put out fresh wood with new holes the following year (once you see your hotel has emptied) to avoid parasites and infections building up.
Nesting tubes & stems
Instead of wooden “bee blocks”, some people use stems or paper tubes. Gather a number of stems that are naturally hollow (such as bamboo, reeds, or teasel). Cut these into lengths between 6″-8″, and bundle them together inside of a container (a plant pot, a tin can, something similar) such that the ends are up against the back of the container. If you cut each just below the stem node, you will get a nice sealed end at one end. In early spring, mount the container on a tree or post several feet from the ground, such that the tubes are parallel to the ground.
Ideas, instructions, and pre-built bee homes
Here are a few DIY designs from which to choose, along with more information:
- Nests for Native Bees (Xerces Society PDF)
- Tunnel Nests for Native Bees (Xerces Society PDF)
- How to Make and Manage a Bee Hotel: Instructions that Really Work (PDF)
- 5 Ways to Increase Nesting Habitat for Native Bees (Xerces Society)
And here are some award-winning bee nest boxes from Nurturing Nature, highly recommended!