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Eugene Weekly : Gardening : 5.14.2009

 

Buzz Buzz Buzz

Let’s hear it for the mighty pollinators

by Rachel Foster

Lots of people are keeping honeybees these days. That seems like a good idea, since wild honeybees have more or less disappeared. Keeping bees increases the bee population generally and provides pollinators for your own garden (and the possibility of your own honey). 

Bumblebee. Photo: Robin Cushman

Like most people, I am alarmed by colony collapse disorder, mites and the decline in honeybees. After all, much of the food we eat is dependent, directly or indirectly, on honeybees. Conventional mass production of tree fruit and almonds would be almost impossible without this colony-dwelling bee that can be driven about the country in hefty numbers and put to work wherever bees are needed to pollinate enormous monocultures. No wonder honeybees are stressed out. 

Unlike a Central Valley almond grower, however, the average home gardener should be able to get by without the honeybee, which is not native. A healthy population of native pollinators could probably do the job. There are thousands of native bee species in the U.S., not to mention other types of pollinating insects. Sadly, many of the same factors that hit honeybees affect native bees as well. In fact pollinators of all kinds are disappearing.

One element behind this decline is undoubtedly the loss of pollinator-friendly habitat, through development, conventional agriculture and widespread pesticide application. Native bees are affected too; they are also becoming infected with diseases and parasites spread by honeybees. All the same, non-honeybees outnumber honeybees in my garden. Bumblebees have been particularly conspicuous.

Like honeybees, bumblebees are social insects, forming small colonies. Other kinds of native bees (mason bees, for example) are solitary; that is, individual bees don’t interact with one another. There may be many about at the same time, but they don’t cooperate. 

The value of native bees in agriculture is beginning to get some attention. Bumblebees, it seems, venture out at lower temperatures than honeybees and even tolerate a bit of rain — valuable traits if you have early-flowering crops to pollinate. And all native bees, adapted to their work by coevolving with the plants they pollinate, can be as much as 100 times as efficient at it. 

While many native bees are specialists, visiting only a certain kind of flower, bumblebees and some others are “generalists” that are happy to visit your apples, squash and so on. What can we do to encourage them? Solitary bees lay their eggs in bark crevices and hollow stems, and occasionally in man-made, purpose-built accommodations. Some bees need a certain amount of bare, uncultivated ground (without a thick covering of bark mulch!). Bumblebees nest in cavities in the ground, or beneath planks or inverted plant pots. 

Slightly untidy gardens may have the edge here. Pesticides are out of the question; needless cultivation should be avoided; debris piles and weed patches are great. When it come to nectar sources, many of the plants that attract the honeybee also attract native generalists. Lavender and oregano, both from the Mediterranean, are magnets to both. Native plants, however, have been shown to support a larger and more diverse population of native insects, including bees. A quick Internet search for “plants for pollinators Oregon” will yield a wealth of information.

Rachel Foster of Eugene is a writer and garden consultant. She can be reached at rfoster@efn.org