Bees are pulling a disappearing act. Honeybees are vanishing from their hives. Bumblebee numbers have crashed so radically that some species are believed extinct. Even native solitary bees are in decline. Food supplies dependent upon pollinators are threatened.
But gardeners can help.
There is no single explanation for what is causing the pollinator losses, said Matt O'Neal, an associate professor of entomology at Iowa State University.
"There are multiple sources of stress," he said. "There are your basic pests, also pathogens like viruses, pesticide exposure and land use practices reducing the kinds of forages bees can feed on. It looks like a combination of all those."
As insect pollinators, bees broaden our diets beyond meats and wind-pollinated grains. An estimated one-third of all foods and beverages are made possible by pollination, mainly by honeybees, the U.S. Department of Agriculture says. Pollinators also are essential for flowering plants and entire plant communities.
"Common species are disappearing at a dramatic rate. I'm terrified in the extreme," said Mace Vaughan, pollinator program director with The Xerces Society for Invertebrate Conservation in Portland, Ore. "I worry in particular about pollinator species with limited ranges and that have unique habitat requirements that are being threatened. A lot of species are dropping out of the landscape."
You don't have to become a beekeeper to restore or boost bee populations. Gardeners can:
• Plant flowers and create green spaces, especially in urban areas. Leave patches of bare soil, rocks and brush piles for use by ground-dwelling native bees. Add caterpillar host plants. "I can't recommend particular plants for all areas of the country but I can recommend the concept," O'Neal said. "Provide pollen and nectar throughout the (growing) season. Plant the right habitat. Every state has land grant agencies and agents. Look to them for help."
• Install bee hotels around the yard by drilling holes in wood blocks and creating reed or bamboo bundles. They provide instant habitat and can be built on the cheap. "Another thing you can do is plant woody plants (elderberries, raspberries, sumac) with branches that have soft insides," Vaughan said. "Grow these shrubs up and then cut them back to expose the stems. Carpenter and mason bees will nest in them."
• Eliminate or change the way you apply pesticides. Don't use them on plants that are blooming. Apply them at night when bees are less active. Spray from ground level to reduce drift, and create buffer zones next to agricultural areas. Rethink the use of herbicides, which reduce pollinator food sources by removing flowers from the landscape.
• Add signage to advertise the presence of pollinators. Bees often range several miles from their hives or nests. Place pollinator habitat signs around pastures, community gardens, city parks, bike trails or suburban yards to promote conservation.
What it comes down to is providing at least two important things, Vaughan said: "Plant wildflowers that provide a high succession of bloom. Have home gardens free of chemicals. Get into natural gardening."