Tuesday, November 1, 2011

Ground Nesting Bees

Bees need the same basic things that humans need: a place to live, food, and an environment free of poisons. Many of the important native pollinators nest underground. Among these are bumblebees and numerous solitary bees. These bees prefer to enter the soil in bare areas not covered by grass, foliage, or mulch. One reason many native pollinators are declining is that favorable habitat is becoming increasingly scarce. Modern large-scale agricultural fields are plowed leaving little undisturbed margin for ground nesting bees. Golf courses and home lawns likewise afford little bare ground when they are covered by a turf of grass. To improve the habitat for ground nesting bees which add much to the effectiveness of pollination of many crops some farms are incorporating strips of ground between crop plantings to accommodate the bees. Homeowners may provide habitat by clearing a portion of a garden or landscape planting of mulch and then leaving the ground bare and undisturbed. Bumblebees, like the one in today’s picture flying from her underground nest, often build dwellings in abandoned mouse holes. With a long tongue, bumblebees are effective pollinators of many crops, especially tomatoes and eggplants.

While the decline in honey bee populations since the mid-1980s has been carefully tracked, the status of native bees and other pollinators has not been documented as closely. One large-scale effort to identify the location and population of native bees enlists thousands of citizens to become data-collecting scientists. The program, The Great Sunflower Project, involves observing bees that are attracted to a single variety of sunflower. People, young and old, plant Lemon Queen seeds; and when the plants grow and flower, they identify and count the bees that come to forage. To sign up to participate in the project or view this year’s results, go to http://www.greatsunflower.org/. The participating citizen scientists found a bee every 2.6 minutes, but 20 percent of gardens had no bees at all. The count is important for identifying areas having shortages of native pollinators.

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