Regional Gardening Reports :: National Gardening Association

In the Garden:
Southwestern Deserts
November, 2009
Regional Report

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Holes in a tree stump create nesting sites for native bees.

Native Bees in the Garden

European honeybees and their kin, the Africanized "killer" bees, garner media attention, but many other fascinating native bees are hard at work in the landscape. Arizona authors Stephen L. Buchmann and Gary Paul Nabhan write in The Forgotten Pollinators (Island Press, 1996), "It is estimated that some 1,500 bee species occur within the arid sub-tropical deserts and semi-arid uplands within an hour's drive from Tucson."

Although honeybees live in large groups, which they are ready to defend if threatened, 90 percent of bee species are docile, solitary creatures: a gardener would have to work especially hard to get stung by one of them. As long as you have no allergic reactions, do not fear solitary bees in your yard, while they gather pollen and nectar and locate safe places to raise young. Following are two common bees that you may spot:

Carpenter Bees
These burly linebackers seem to defy the laws of gravity and aerodynamics. About the size of a grape with wings, their metallic bluish-black bodies are easy to see, and hear, as they chug from flower to flower. One species has a yellow male. Unlike some bee species who use existing holes in dead wood for nesting sites, carpenter bees can excavate their own.

Leafcutter Bees
You'll probably notice a leafcutter's handiwork before you spot the smallish grey or black bee. In spring, females neatly snip semi-circle-shaped bits of foliage or petals, which they curl between their legs and carry off to line their nests. Leafcutters seem to prefer smooth, thin plant material, such as bougainvillea leaves and rose petals, but their limited snipping doesn't harm the plant. They collect pollen on bristle-like hairs on their abdomens.

Make a Bee Dwelling
Unfortunately, as native desert habitat disappears to development, potential nesting sites also decline. Bees are important links in the Southwest's ecosystem, pollinating native plants that a broad range of creatures rely on for food or shelter. You can help native bees by creating these simple nesting sites in your landscape:

Some bees burrow underground to build nests, taking advantage of a somewhat cooler, moister environment. Allow a few out-of-the-way patches of bare earth rather than a solid cover of gravel mulch or grass. Place an upside-down clay pot near a garden bed. A bee can navigate through the drainage hole to burrow into the protected soil, while the pot serves as a reminder for you not to dig there.

Many bees construct their nests in beetle or borer tunnels in dead wood. If you can leave a dead tree standing on your property, it provides housing for all kinds of intriguing desert life, including bees. Although a dead tree is not practical for every landscape, a stump with holes works fine.

Build a bee house by drilling holes of various sizes in a block of scrap wood. Different species will be attracted to different sized holes. Try 1/4", 5/16" and 3/8"for leafcutters, 3/4" for larger carpenter bees. Holes should be 3 to 5 inches deep for leafcutters, 8 to 10 inches deep for carpenters. (Holes should be closed on one end.) Secure the bee block to a shady, dry location such as a tree or under the eave of a building.

Provide a bundle of dead branches. If there are no insect tunnels in the wood, drill some holes.

Allow the thick, woody flower stalks on agave and desert spoon to remain on the plant. Or, cut the stalk at its base and poke it into the soil elsewhere in the landscape or lean it against a fence.

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