Tuesday, 23 Sep 2003

TUSCON, Ariz.

A drilled block of lumber, a.k.a. a bee condo.

Illustration: Vera Ming Wong.

Where is that colorful tin? Ah, there it is, amongst my stash of assorted world honeys bursting with flavors. I reach up into my kitchen cupboard and pull down one of my favorites, Leatherwood honey from Tasmania, the huge island off the southeastern tip of the Australian continent.

Honeys are magical. I’m not talking about the ho-hum blended stuff or bland clover honey squeezed from a spout atop the head of a plastic bear, but the really exotic single source kinds. Honeys are the distilled sugars plus volatile essences of myriad wild flowers. I like to think of bottled honey representing the “soul” of a field of flowers, a meadow in riotous bloom. Of course, honeybee foragers collect floral nectars and process them into honey and bee bread, pollen plus added nectar or honey, as food for themselves and their developing brood. They don’t make honey for people, for beekeepers and shopkeepers to steal away with and eat. Still, I’m glad that an unknown Tasmanian beekeeper, in that distant mountainous land, cared for the bees and took away just a bit of their golden liquid treasures, which eventually made its way to my Tucson breakfast table.

The honey is warm and flows evenly over my slice of toast, its distinctive scent melding with the luscious hot bread’s aroma. I can’t wait and bite in, floral odorant molecules from Tasmanian rainforest blossoms hitting my taste buds. Mmmmm good. Cradling a ceramic mug of “tea, Earl Gray, hot,” I walk out onto my south-facing patio to greet my pollinator pets. It’s become daily morning ritual for me during the summer and fall. Houseguests, friends, and relatives who visit are always intrigued by the holey bee real estate under the eaves of my Vega ceiling southwestern patio. “Why, they’re bee condominiums, of course,” I tell them. They gaze up, fascinated by the elongate black bees quickly darting in and out of the rows of uniformly sized and spaced holes leading into the drilled wooden block bee houses. I can sense their wonderment about the mysterious lives these fuzzy insects lead.

It’s a typical Tucson September morning, already 90 degrees outside and not even 9:00 a.m. The bees are actively foraging, with at least a dozen in view at one time. These are native leafcutter bees of the genus Megachile, subgenus Chelostomoides. The females have massive and powerful jaws (mandibles) that they deftly use to cut half-moon-shaped leaf pieces or masticated ones, to carry mud, to gather sticky plant resins, or to transport tiny pebbles and sand grains back home to fashion their nests. I spot several nests that have hot pink fluff sticking out of their entrances. Must be the neighbors’ Bougainvillea shrub that caught their attention. I’m temporarily amused by thoughts of an eclectic individual nesting female Megachile, with a passion for pink colors and a flair for interior decorating.

Massive jaws on a female Megachile prosopidis leafcutter bee.

These ain’t no high society bees. Instead, they lead solitary lives, each nesting female doing her own thing, but they are ever so important as pollinators of the native Sonoran desert plants surrounding my home. From my observations and those of my recently graduated University of Arizona doctoral student, Beth Armbrust, we know that there are three or possibly four closely related Megachile species happily living in my bee lumber. Beth gave colorful names, including “lumpy sand,” to the interesting nest entrance cappings they make. Some of the Megachile bees always use the same materials for sealing off their nests while others switch back and forth between materials. Inside each linear nest, a paper drinking straw inserted into the drilled holes, up to 10 or more bee larvae are contentedly gorging themselves on pollen and nectar food provisions left by mom. The females have no contact with their offspring after laying an egg and sealing it in. Soon, the fat bee grubs will spin cocoons and wait it out until next year. Although some of these species have two generations per year, all of the bees I’m watching today won’t emerge as new adults until either the spring or summer of 2004. That’s the way of life for most of this country’s solitary bee species, about 3,950 ground and twig or wood-nesting species.

One female Megachile backs out of her nest while another sits nearby.

Looking over my back wall, I can see a large, gray, dead Palo Verde tree. I’m glad the neighbors haven’t cut it down. From closer inspections I know that its trunk and branches are riddled with holes as if peppered by a series of shotgun blasts. These holes are the handiwork of tunneling buprestid and cerambycid beetle larvae which have long since chewed their way through the bark of the dead tree and emerged as adults. These holes are vitally important for maintaining populations of native leafcutter and mason bees (called that since they trowel in mud into their nest architecture). The beetles move out and the bees move in. It always amazes just how quickly nesting female leafcutter and mason bees find the latest bee real estate in the neighborhood. Often when I first place a new bee condo under my patio eaves, I spy a female checking it out within minutes. Location, location, location! Most of these bees can’t excavate their nests in the wood but are entirely dependent upon beetle hand-me-downs. It’s important to keep dead trees and limbs in areas where bees and other wildlife live. Woodsman, spare that limb — it’s a move-in special for house-hunting bees.

You can help protect and conserve native leafcutter bees in your neighborhood by creating a bee condo out of some discarded lumber. Just drill some holes about three to five inches deep into the face of the lumber. Don’t drill all the way through the lumber. A drill bit 5/16th inch diameter (7-8 mm) is a good general-purpose size for your bee holes. Securely fasten your new bee house under the eaves against your home or a garden shed, where it’s protected from the rain. Have fun. Experiment with smaller hole sizes and see who shows up. Don’t worry about a few neat circular snips taken out of those rosebush leaves. The leafcutter bee leaf-procurement activities won’t kill your plants and you’ve donated essential building materials to a growing bee family nesting somewhere nearby. In return, they will provide you with essential pollination services for native plants and garden crops in your yard and surrounding areas. Not only that, but they can entertain you for hours as tiny but exquisitely watchable wildlife. Become a bee watcher. For some real fun, get a pair of close-focusing binoculars and really get to know them in an up-close-and-personal way. Watch ’em as closely as you like, they won’t sting you — but you may be stung by a growing curiosity to explore their fascinating ways of pollinating flowers and making a living from them.