It’s a still, warm, early spring morning at Garden in the Woods, and the sun glances off the first wildflowers of the season. I’m walking softly, almost creeping toward a large bed of blooms, watching intently and feeling a little silly. I’m not hunting marauding deer, hungry rabbits, or even a sleepy dormouse. I’m stalking the wild bees, butterfly net in hand. It’s early for bees, but some are already flying: bumblebees and carpenter bees, Andrenid bees and Mason bees, and various others, mostly small and inconspicuous. 

 

By catching these and identifying them, I hope to establish a baseline on bee diversity in the Garden. The smaller bees are attracted to the yellow trout lilies today, bypassing the violet Virginia bluebells, the white Dutchman’s breeches, and the pink bleeding heart. Suddenly I hear the approaching drone of a bumblebee, which stops in a patch of wildflowers for a quick pick-me-up before flying to examine the bases of nearby trees for a hole that might serve as a nest to raise its brood. Farther on, a huge carpenter bee hovers inquisitively in front of the sunny wall of an old shed.

 

At your service

 

All bees visit flowers in their quest for nectar and pollen, and most will visit whatever is blooming. Although a few bees specialize in a single plant species, you can generally expect to see a variety of bees visiting a given plant. As they buzz around collecting food, they unintentionally act as a door-to-door pollen delivery service, providing the plant with a crucial step in its life cycle. If you have edible fruits in your garden, you may notice that good pollination will increase your yield of apples, blueberries, and many others. And although most plants have a backup plan against temporary pollinator failure—clonality, self-compatibility, or just longevity—in the long run, without pollinators a lot of plants would die out.

 

The buzz on native bees

 

The soft humming noise warning you not to put your nose too close to that fragrant azalea blossom comes from the flight muscles of a bee. Her buzzing while still inside the flower tells you right away that she’s not a visitor from your neighbor’s honey bee hive. Instead, she’s one of many species of native bees, those humble bumblers and underappreciated providers of sexual services to flowering plants. When a honey bee lands on a flower, it settles in for a moment and stops buzzing while it rummages for nectar and fills its leg pouches with pollen. But many native bees have another trick up their fuzzy sleeves: They’re able to disengage their flight muscles from their wings, causing their whole body to vibrate. This “buzz pollination” shakes pollen right out of the anther like salt from a shaker. In plants with hard-to-reach stamens (cranberries, blueberries) or tubular stamens (tomatoes, peppers), buzz pollination is especially effective for increasing fruit yield.

 

For this and other reasons, native bees are vastly more efficient pollinators than honey bees. Sheer numbers and portability give the honey bee an advantage (see sidebar). But native bees emerge earlier in the spring, start work earlier in the morning, fly more quickly from flower to flower, and deliver more pollen to receptive stigmas.

 

Biodiversity and bees

 

Of course, bees are not the only native pollinators. Butterflies, hummingbirds, wasps, flies, bats, and beetles do their share, but bees are by far the most important, performing some 85% of animal-mediated pollination. And they have been around for a long time, at least 120 million years. Today there are over 4,000 species of native bees in North America. They include bumblebees, cuckoo bees and carpenter bees (family Apidae), mason bees and leafcutter bees (family Megachilidae), sweat bees (Halictidae), plasterer bees and yellow-faced bees (Colletidae), and Andrenid bees (Andrenidae).

 

Every species of bee feeds on nectar and pollen, so nearly all are pollinators, but otherwise they differ hugely from one another. For instance, only bees in the family Apidae are truly social (like honey bees), living in a hive with a queen and workers. The rest are “solitary,” which means that each female, after being fertilized by a male, builds her own nest and lays her eggs in it. The eggs develop, with little or no parental care, and each new bee that hatches out goes off on its own.

 

How to increase native bee abundance and diversity

 

No matter the size of your garden, you can do plenty of things to encourage native bees. As with any animal, a bee’s main needs are food and shelter. To enhance food availability, plant a variety of flowering trees, shrubs, and perennials so that something is always in flower, spring through fall. Shelter can be hard to come by and bee populations are often limited by housing rather than food. Different bees require different resources for shelter, so if you want to maximize diversity of native bees in your garden, try the following suggestions.

 

First, allow for some undisturbed habitat in a corner of your garden, where you don’t mow, prune, or weed, as a lot of bees are sensitive to disturbance. Create a brush pile in an inconspicuous shady spot. To make nesting habitat for digger bees and other ground-dwelling solitary bees, remove the vegetation in a small sunny area, and if your soil isn’t very sandy, dig a hole and fill it with a soil/sand mixture. Finally, if you have a snag (standing dead tree), remove some of the bark, and it will be used by carpenter and mason bees.

 

If you lack space to create these natural habitats, don’t despair. You can build several types of native bee shelters that won’t look out of place even in a small urban garden. Mason bees, leaf-cutting bees, and other solitary bees will use tunnels drilled into wood blocks, or hollow stems such as reeds, teasel, or bamboo. Cut these in six-inch lengths with one end closed, and put bundles of them in a sunny spot, protected from wind and rain. The more tunnels you can make available (in different diameters for different species), the more bees you will have the following year. Bumblebee nests can be made from wood boxes with a ¾-inch diameter entrance tube and some cotton pillow-stuffing inside (they usually take over abandoned field-mouse nests). Place these close to the ground in a shady spot. Look for native bee homes throughout Garden in the Woods. For instructions on building shelters for native bees, visit the Xerces Society for Invertebrate Conservation at www.xerces.org.

 

Even before you have enhanced your garden’s bee habitats, you can enjoy the insect activity at blooming plants on a warm afternoon. You may be astonished at the variety of insects that will pay a visit. You can distinguish bees from wasps: Most bees are fuzzy; most wasps, hairless. Some flies are impressively disguised as bees, but flies lack antennae (and have only two wings instead of four, though this can be harder to see). Honey bees may still be common, but you will see the larger bumblebees, the smaller (sometimes metallic green) sweat bees, and dozens of others ranging in length from an eighth of an inch to an inch or more.

 

As you watch them come and go, gathering nectar and pollen at your favorite blooms, you can delight in the knowledge that, just by gardening with native plants, you are increasing the abundance and maybe even the local diversity of our amazing native pollinators—those really busy bees.

 

Native bees and the honey bee crisis

 

The cause of the recent decline in honey bees (Apis mellifera) remains mysterious (viruses, mites, pesticides?). Honey bees are not native to North America, but they provide important services by making honey and pollinating many commercial crops, from almonds to watermelons. Hives are trucked from farm to farm and rented to commercial growers. Brought in just in time to fertilize cranberries or peaches so they set tons of fruit, the bees are then whisked off to the next farm, leaving the grower free to apply pesticides.

 

The honey bee decline is hurting the bee business and sending the cost of some crops soaring. In response, some growers are looking at alternative pollinators, especially native bees. A few species have been cultivated to replace honey bees for certain crops. But for most crops, the only alternative is wild native bees, which can be encouraged by reducing pesticide use and setting aside fallow areas and hedgerows for nest sites and alternative food sources (native flowering perennials).

 

In short, the honey bee decline may actually have a silver lining: It may lead to more sustainable farming practices and a greater appreciation for our native pollinators. As pollinators, native bees outperform honey bees on a bee-per-bee basis, but getting enough of those busy little natives happily buzzing around your orchard—that’s the challenge.