Bumblebees—The Essential, Indefatigable Pollinators
On hot, lazy summer days I like to go out in my garden, flop down on the old chaise lounge, sip a margarita, and watch pollinators at work on my flowers. Butterflies are the divas of these botanical love fests, captivating with their flamboyant colors, stripes, and spots as they flit from bloom to bloom. Hummingbirds are the acrobats, zipping up, down, sideways, and even backwards to probe long-throated, ruby-colored blossoms. Bumblebees are the workaholics—diligent and dependable, but a little dorky as they lumber around the garden.
The bumblebee isn't the most glamorous insect around, but the lovable bear of a bee surpasses even the celebrated honeybee in the industriousness department. Bumblebees are often up and out of the hive before dawn, way before the honeybees, and they're frequently still hard at work after the sun has set. In fact, the bumblebee is one of the world's most proficient practitioners of the pollinating arts. Its distinctive striped fur coat is tailor-made for attracting pollen, and the plump pollinator is built like a Mack truck to carry a lot of cargo.
We live on a planet pollinated primarily by bees. Bees fertilize most of our favorite flowers, and pollinate a third of the plants we eat. Bumblebees are important pollinators of tomatoes, eggplants, peppers, melons, raspberries, blueberries, cranberries, strawberries, and many other crops, and are the only known pollinators of potatoes worldwide. They are also the exclusive pollinator of several rare and imperiled wildflowers, including native monkshoods and lady's tresses orchids. Without these essential insects, farm productivity would plummet and wildflowers would become extinct. In short, bumblebees and other bees are essential for our own well being and the survival of a good deal of the world's biodiversity.
But bees are in trouble. In recent years, parasitic mites have killed most feral honeybees and many colonies maintained by beekeepers. Meanwhile, the natural habitats of bumblebees and other native bees, which were pollinating North America long before the colonists arrived with their European honeybees, continue to be carved up, destroyed, or degraded. However, we all can help improve the lot of bumblebees by planting the flowers they love, whether we garden on an acre or in a window box. One small bumblebee garden may not seem like much, but as these patches of backyard habitat multiply across the community and the country, they can play a vital role in feeding and protecting threatened pollinators.
My Shelter Island, New York, garden is jam-packed with monkshoods and other bumblebee magnets. I grow them in my wildflower border, in a tiny meadow I've planted for pollinators, in pots on my patio, and in the shady woodlands that surround my house. All season long, my yard is buzzing as the chubby bees work the blossoms.
I also plant lots of the blue, purple, white, and yellow flowers that bumblebees love best. In order to provide a steady food supply, I try to have some of their favorite flowers blooming from spring through fall, when they are active. I garden mostly with native wildflowers that evolved in this area, because they are best adapted to the local soils and climate—and the local pollinators. And I never use insecticides, which harm bees and other beneficial bugs. If a garden plant can't survive without poisonous chemicals, I figure it's not worth growing.
Bees are not only the workaholics of the insect world but also the cupids of the plant world. As they buzz along from flower to flower, collecting food for the baby bees back at the hive, they're also facilitating plant reproduction. Botanist Peter Bernhardt, author of The Rose's Kiss, calls them "a flower's winged penis."
Plant sex differs from human sex in that it typically must be consummated by a third party, whether the wind, a hummingbird, or a bumblebee that transfers pollen from one blossom to another. To lure bumblebees and other intermediaries, plants clad themselves in colorful flowers with seductive scents. While the bee is fertilizing the flower, the plant is returning the favor, offering nectar, the insect equivalent of soda pop, and/or life-giving protein in the form of pollen.
Some flowers are especially suited for pollination by bumblebees, having evolved a number of characteristics suited to the creature's girth, behavior, and other attributes. Unlike humans, bees can see ultraviolet; many of the flowers we see as white, they see as ultraviolet. They not only see this color but also are attracted to it, making a beeline to flowers in the ultraviolets as well as the blues and purples that dominate one end of the color spectrum, though they're attracted to yellow blossoms, too. Many of these flowers have bizarre wavy lines or leopard-like spots on their petals that serve as signposts pointing the bees toward the nectaries, where nectar is produced and the insects can satisfy their serious sweet tooth.
Many bumblebees are so-called long-tongued species with a lengthy, tube-shaped schnozzola called a proboscis that holds the tongue. They use this apparatus to probe the deep recesses of elongated blooms and suck up nectar. Not surprisingly, the petals of bumblebee flowers often form elegant, elongated bells, funnels, or tubes, with the nectaries hidden deep inside. In some species, the nectar is hidden at the end of a long, hollow floral structure called a spur. In these ways, the plants make sure that the precious liquid gets only to the bumblebee, the animal most capable of accomplishing pollination.
The attribute for which the bumblebee is best known, apart from its luxurious striped pelt, is probably its heft. The flowers that cater to this plus-size pollinator must be robust, because, unlike the acrobatic hummingbird, the bumblebee has to perch on or cling to them in order to sip nectar and collect pollen. That is why the blooms of many snapdragons, mints, orchids, peas, and other flowers have modified lower petals—lips, aprons, or keels—that serve as sturdy landing pads. Moreover, bumblebee blossoms often come equipped with some form of physical barrier that only the bulky insect can surmount. For example, in the flowers of many members of the pea family, the nectaries, along with the sexual organs, are enclosed in the two lowermost petals that are joined together to form the keel. When a bumblebee lands on the keel, its weight forces the petals to pop open, exposing the flower's private parts.
No blossoms are more beautifully adapted to pollination by bumblebees than the monkshoods (Aconitum species)—in fact, they depend entirely on bumblebees for pollination. As the name suggests, the petal-like upper sepals of a monkshood flower form a large, erect, helmet-shaped hood, which conceals two long spurs with huge nectaries at the end reachable only by long-tongued bumblebees. A bumblebee visiting an Aconitum lands on the lower sepals. As it heads towards the nectaries hidden in the hood, it clambers over the male and female parts of the flower and is dusted with pollen. When it flies off to the next monkshood blossom and deposits some of this pollen, the bee completes its part in the continuation of the species.
In spring, my Shelter Island woodland garden is a wash of pastel purple when the violets, bumblebee favorites, bloom among glades of fern I've planted along paths and around the house. One side of my patio brushes up against the meadow, which is abuzz with bees in June when the blue wild lupine blooms. The bees are wild about the tall purple spires of blazing stars that bloom in summer. From September until late October or early November native asters and goldenrods are the main attractions. On the other side of the patio, my pollinator garden continues in a dampish area. Here is a border of wetland bloomers laden with bees (and butterflies) for weeks in summer, including joe pye weed, with huge domed heads of dusty mauve flowers on eight-foot stems, and sweet pepperbush, with fragrant spikes of white flowers.
Although native wildflowers are the most reliable sources of bee food, I do grow some traditional garden flowers and herbs in big old galvanized tubs on the patio, and the neighboring bumblebees don't seem to mind a bit. They are especially fond of fragrant white or purple heliotrope and herbs like borage, whose star-shaped, fuzzy blooms are the color of the sky on a perfect June day. I choose classic single-flowered varieties of old-fashioned cottage garden plants such as snapdragons, avoiding the newfangled cultivars with double blossoms. Breeders typically have size, shape, or color in mind when they create these varieties, not the most nutritious pollen or maximum nectar production so important to bees. In the words of entomologist and bee specialist Stephen Buchman, these plants "are often all show and no bee chow." For example, while old-fashioned single larkspurs are a favored source of sweet nectar for long-tongued bumblebees, varieties with double flowers lack the spur for which the plant is named, as well as the nectar stored in it. Likewise, bumblebees straddle the small flowers of violets to sip nectar, but they can't manage the much bigger blossoms of pansies, their more cultivated cousins.
Often, it isn't a lack of flowers that limits native bees but rather real estate. This isn't a problem in my mostly wild garden, but the manicured turf and flowerbeds of suburbia offer few suitable nesting sites for social bees like bumblebees. Old mouse nests or rodent burrows are the preferred abodes, but bumblebee hives have also been found in deserted bird nests, rubbish piles, and thick, cushioned clumps of moss. If there are no abandoned bird nests or rubbish piles in your yard, you can buy a prefabricated bumblebee nest box. One example is the Humble Bumble Home, offered by a Washington-based, family-owned business called Knox Cellars (www.knoxcellars.com). It consists of a pine box, soft cotton nesting material, an instruction book on the life history of the bumblebee, and a clear plastic "ceiling" that allows you to lift the box's wooden roof and observe the busy bees at work. I haven't tried one, but I hear that bumblebees do take up residence in such structures, whether pre-fab or homemade.
Creating a healthy habitat for bumblebees does not require great horticultural talent. These are not shy, finicky creatures. You don't have to re-landscape your entire property; just tuck favorite bumblebee blooms between your existing plants, or grow them in pots where you can observe the insects up close. Then sit back with a long, cool drink and enjoy the show.