Over the last several years, colony collapse disorder has devastated honeybee populations, claiming almost a third of the nation’s hives. It’s not just honeybees that have suffered. Gardens and farms nationwide are humming with thousands of native bee species, many of them just as important—and just as threatened—as the honeybee.
While scientists work to pinpoint the causes of colony collapse, anyone with a yard or garden can help native bees, including the sweat bee, the orchard mason bee and the bumblebee. One of the best ways to do so is by building a simple bee house where they can find refuge.
A Home for the Humble Bumble
Consider the humble bumblebee. Tomatoes (also native to the New World) cannot be pollinated by honeybees, so every bowl of salsa and jar of pasta sauce owes its existence to the stubby bumblebees that pollinate those little, yellow tomato flowers. Why not build a little chez bumble near the compost pile?
Bumblebees need all the help they can get. “Native bee populations have been hammered hard, especially the bumblebees,” says Alan James Molumby, Ph.D., a clinical assistant professor of biology at the University of Illinois at Chicago.
The culprits? Changing agriculture practices and parasites. Every inch of farm fields is now plowed and planted, leaving little refuge for native bees. Moreover, honeybees—introduced to the Americas by European settlers—brought with them a host of parasites that have devastated populations of native bees.
A bee house offers a welcome refuge. To make one out of a chunk of untreated wood, drill holes at least three inches deep using drill bits of different widths. Then, hang it in a sunny area at least five feet off the ground. (“If you put in the shade, it will fill up with spiders,” Molumby says.) Bumblebees and other native bees will soon take up residence inside the tunnels.
Another kind of bee house can be made with an empty clay pot. Plug up the drainage hole in the bottom and lay it top-down on a sunny patch of soil. (The south side of a building or trees tend to be the sunniest.) Use fingers or a shovel to dig little divots under the lip so that bees can crawl in and out.
Alternately, for $20, there are adorable bumblebee houses available online. Once the bee house goes up, leave it alone. An occupied bee house may be defended by residents’ stings. Or maybe not. Native bees tend to be less aggressive than honeybees. Mason bees rarely sting. The males actually lack stingers.
Once the bee house is in place and “rented” for the season, gardeners and homeowners can do a number of other things to be a good bee landlord:
1) Ditch the roto-tiller.
Bumblebees and other native bees like to nest in the ground. So tilling over the soil every spring can literally destroy their homes. Instead, Molumby suggests that gardeners consider adopting a no-till approach. Simply clip off the dried stalks of last year’s crops at ground level without bothering to pull up the roots. This approach requires less work, it helps bees and it leaves other beneficial structures like fungi and earthworm tunnels in place.
2) Plant lots of flowers.
Molumby says that native bees, like their honey-making kin, benefit from a variety of flowers. Flowering native plants will work best because they are precisely the sorts of food sources that native bees evolved with. “Those trays of impatients and bedding pansies do nothing for pollinators,” Molumby says.
In their place, Molumby suggests easy-to-grow natives like sunflowers and members of the mint family. Bees need access to flowers for the whole season, so make sure to plant varieties that will bloom at different times
Keep in mind that bees can be highly specialized in terms of the flowers they feed on. The adorable little squash bee depends upon its namesake plants. So don’t plant squash varieties for just one season; plant them year after year to help build up squash bee populations. Ditto for sunflowers and mint.
3) Above all, don’t spray.
“Bees hate artificial pesticides,” Molumby advises. Pesticides targeting other insects can still wreak havoc on bee populations. It seems, for instance, that a group of pesticides aimed at corn pests may trigger colony collapse. Whenever possible, use row covers instead of chemical pesticides. Doing so protects more than favorite plants; it also safeguards all the bees in the neighborhood.
CHRISTOPHER WEBER (christopherweber.org) is an environmental journalist, community gardener and stay-at-home dad. He writes The Built Environment blog for E.