Out here in the Sonoran desert, the vast majority of native bees are both solitary and burrow in the ground for brood cells for their babies. There are also leaf cutter and mason bees here who use previously made beetle tunnels in old wood. And all of the native bees are, obviously, adapted to eating native foods.
So, what can we do to encourage these lovely insects to stick around and pollinate our yards?
1. Provide Housing.
This pdf is very useful for what type of housing encourages bees that use tunnels from boring beetles: http://www.xerces.org/wp-content/uploads/2008/11/nests_for_native_bees_fact_sheet_xerces_society.pdf
It's aimed at gardeners in Oregon, but a lot of the information is still valuable, especially for our leaf cutter and mason bees. The one addition we need to think about here in the desert is the availability of substances the bees can use to make a capping plug for the cells they are using to grow new bees. Here in the desert, they may use leaves, resin, pebbles, or mud. For a lot of us, none of these are readily available in our yards unless we provide them specifically. So if you can provide these materials, even clearing a small section of dirt near where a hose or spigot drips so that there is some available mud, it may help attract more bees to come settle in your yard.
Bees that burrow into the ground for their nests require, well...ground. If you have a yard that is mostly rock on top of plastic, then there is nowhere for the bees to make their nest except in your garden, where you are digging enough that it would likely disturb any nest they tried to make. Bare earth, well-drained typically, is required to attract ground burrowing bees. And as I said previously, ground burrowing bees are the most common bees in the Sonoran Desert. So making some bare dirt patches in your yard is actually a good thing to do for both the bee population and your yard.
Different bees may have different requirements for their nests. Different slopes and potentially a variety of soil types are required, although most bees are going to want homes that are safe from digging and getting stepped on. Providing sandy soil, bare plain native dirt, and even dirt that is upright, like an embankment would be, can all provide homes for various types of ground burrowing bees. I have not yet researched which bees have which soil requirements, so it's probably a good idea to provide a little bit of everything at first and see what the bees near you prefer. A few patches of bare earth may be enough.
Most of our native bees mate in the spring or summer, soon after they emerge from their cells as adult bees. Because most bees here only have one brood, with babies emerging the next year, you'll need to plan ahead and provide homes this season for bees in your yard next season.
2. Provide Food.
There are lists upon lists of flowering plants that will attract bees. In fact, here's a couple for the desert:
Desert plants for pollinators: http://www.aznps.com/documents/SelectingplantsforPollinators.pdf
Desert Seed Store with bee-friendly plants: http://www.desertseedstore.com/category/Attracts-Butterfly-Hummingbirds-Bees-66
One of the important tips you'll find out is what color of flowers most attracts bees out here: yellow, white, blue, or ultraviolet (yeah, I have no idea what that one's gonna be).
Something that is not mentioned much more than in passing is this: what are the bees around you eating in terms of native plants that you didn't have to plant yourself? If you want to know, spend some time out in your garden at various times in the day and see where the bees are going. Let some of the native weeds grow in your yard and learn what they are. Not the names, although that can be fun, but what they are to your garden. In this case, the important question is: do these weeds flower and if they do, are they attracting pollinators?
|a Lyreleaf Jewelflower, which grows wild in my yard|
Varieties of bees are not all pollinating the same types of flowers. Your sunflower is going to need one of the larger bees while dill or cilantro are going to require one of the smaller ones. So cultivating a variety of sizes of native, flowering weeds can actually attract a variety of bees to your yard, without any watering or effort on your part. I tend to let these flowering weeds grow on the outskirts of my gardens.
Previously, I've just let weeds grow and flower where they will. This year, I'm trying to improve on the practice. I'm going to be collecting the seeds of some of these weeds and spread them near the gardens where I think they'll be most useful. The large, yellow flowers that require big bees? Put them near my sunflowers. The tiny white ones that attract the smaller bees? Put those near my gardens with lots of cilantro and dill.
|Like this little guy|
Some of the larger weeds can even grow tall enough to even provide shade, if you put them on the west side of your garden, so I'll be doing that this year, as well. It's not perfect, as some of these weeds I can't yet identify so I have to judge whether they are 'stealing' too much water and other resources from my nearby garden by experimentation alone. Some weeds might have chemicals that inhibit the growth of my garden plants, or cause other problems - without knowing what these are, I just have to fiddle a bit and see what works.
But in this economy, having plants that were free, required no extra water and little to no effort to grow, but still attracted pollinators? That's definitely what I want! And besides, it's very peaceful to spend just a few minutes a day watching the flowers to see what drops by. :-)
For anyone who is interested in learning about bees themselves, here's more information:
A lot of my information on bees was acquired here - http://www.desertmuseum.org/books/nhsd_bees.php
Information on solitary bees: http://www.earthlife.net/insects/solbees.html
Handout for kids: http://www.fs.fed.us/wildflowers/teacher/documents/k5_DesertGardeners_nativeBeeHandout.pdf
Teacher information to go with the handout http://www.fs.fed.us/wildflowers/teacher/documents/k5_DesertGardeners_nativeBees.pdf