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Published June 15, 2008, 12:00 AM

Encouraging bees good for farms and food

Bees have been making headlines across the United States this year, as scientists endeavor to understand such problems as “Colony Collapse Disorder.”

By: Jim Stordahl, DL-Online

Bees have been making headlines across the United States this year, as scientists endeavor to understand such problems as “Colony Collapse Disorder.”

Keeping bees healthy is important because bees pollinate about a third of all fruits and vegetables eaten by humans. So, bees are particularly valuable for fruit and vegetable growers.

The story is more complicated, and interesting, than you might think. While every child knows about hard-working bumblebees, few of us realize that there are 4,000 species of native bees in this country.

Some species of native bee are familiar, such as the bumblebee. Many are unfamiliar, though they live in our yards and gardens alongside us. Unlike honey bees, native bees generally do not sting, generally do not form colonies, but do come in a bewildering variety of colors, sizes and shapes. You can often recognize native bees because the hairs on their bodies are covered in pollen.

These bees are worth encouraging, because they can pollinate alfalfa, apples, blueberries, tomatoes, peppers, squash and other important crops. Because native bees already live here, it is fairly simple to encourage them. On farms, planting native prairie flowers along field edges, along field roads, and in neglected corners of a property, gives wild bees food and habitat. Because prairie seldom needs mowing, the flowers are left to provide nectar and pollen. Many bee species live in wood, so letting sumac, elderberry and blackberries grow, and leaving some dead trees alone, will provide habitat.

Other native bees nest in the ground, spending most of their lives in a larval state. Tillage will kill the larvae, so leave some places untilled. In short, some of the best places for bees are the worst places for growing crops.

If you grow apples, blueberries or other fruits, interplant cover crops between rows and let them flower. Possibilities are clover, vetch or yarrow. Good garden plants for bees include zinnia, thyme, basil, mint, sunflower, hyssop, Joe Pye Weed, gay feather (Liatris), cosmos, cleome, globe thistle, giant hyssop and the aptly named bee balm (Monarda or bergamot).

For those of you who love your electric drill, you can take a block of untreated wood and make “bee houses” for native, solitary bees, such as the mason bees and leafcutter bees. Take a block of wood at least four inches square — a log, dead tree or firewood also works well, and drill a variety of nest holes about three-quarter inch apart.

Drill one-quarter-inch holes as deep as you can, up to five inches deep. Drill 3/32 or 3/8-inch diameter holes five to six inches deep, if you can. Don’t drill all the way through the wood. (Obviously, your block of wood must be at least six inches deep). Drill a clean hole with a sharp bit, and drill across the grain of the wood. Fasten them tightly to a post about four feet high, facing southeast towards the morning sun.

After two years, get your drill out again and replace the whole block, to keep diseases at bay.

For much more on bees, see the Xerces web site at www.xerces.org. You can also contact me at the Polk County Extension office in McIntosh or at the Clearwater County Extension office on Wednesdays. Our toll free number is 800-450-2465. If e-mail is your thing, contact me at stordahl@umn.edu. Source: Tom van der Linden, Extension Educator, Winona County.

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