Spring and early summer days are filled with wildflowers and insects. While resting along a pathway at Bald Hill Farm last weekend, I watched numerous bumble bees (Bombus spp.) alight on the petals of a nearby wild rose bush and extract pollen from the stamens. Their hind leg hairs (corbicular fringe) were ablaze with yellow grains of pollen.
Bumble bees range mostly in northern temperate ecosystems in part because they have learned to use solar radiation, shivering and other internal mechanism to raise their body temperature and function in colder weather. A hardy bumble bee (Bombus polaris) forages through the wind-swept arctic tundras of Ellesmere Island with musk ox, arctic foxes and wolves. Other Bombus species roam the high mountain meadows of the Sierras and Cascades. Bumble bees are social insects, form colonies, and nest generally on or in the ground with a queen and workers. About 50 species of bumble bees are native to North America including the parasitic cuckoo bumble bee which are somewhat indolent and don’t collect pollen. They invade nests of other bumble bees, kill the queen and use the resident worker bees to raise their young.
The Xerces Society states that 70 percent of the world’s flowering plants, including most of the world’s food crops, need pollinators such as bumble bees to complete their reproductive cycles. Bumble bees are less important than honey bees for commercial pollination, but they are generalists that select from a wide range of plants across many diverse habitats. They pollinate many berry crops and are the primary pollinators for greenhouse peppers, eggplants and tomatoes. In early spring bumble bees pollinate the fields where I pick blueberries in late summer. They are profoundly important pollinators of native flowers in many natural ecosystems distributed across their range.
Many bee populations including bumble bees are declining. The Xerces Society listed five species, western, rusty patched, yellowbanded and American bumble bees, as potentially declining in abundance and distribution. Franklin’s bumble bee, once found in southwest Oregon and northwest California, was last observed in 2006 and with great sadness may be extirpated. Scientist and artists in Great Britain have created an opera “Silence of the Bees: A Science Opera” dedicated to raising the awareness of the dramatic loss of bumble bees including the near extirpation of the great yellow bumblebee that once roamed the valleys and hills of Great Britain. There are likely many causes for the declines of bumble bees including habitat fragmentation and degradation, pesticide use, pathogens and competition with introduced bees.
A little over fifty years ago, a book was published with the opening line “There was once a town in the heart of America where all life seemed to live in harmony with its surroundings.” A few paragraphs later the author wrote- “Then a strange blight crept over the area and everything began to change. Some evil spell had settled on the community.” It sounds like an extract from J.R. Tolkien’s “Lord of the Rings” but in fact was the beginning of a chronicle called the “Silent Spring” that described the poorly regulated use of chemicals and the impacts these chemicals may have on wildlife and people. There a many arguments on both sides of the aisle when discussing the costs and benefits of agricultural chemicals and regulations to minimize the impacts of these substances have come a long way since Rachel Carson wrote the opening line of Silent Spring. However, the importance of Rachel Louise Carson’s account in “Silent Spring” was the recognition that humans have a responsibility to try to fix what they break. The Oregon Department of Agriculture recently attributed the deaths of tens of thousands of bumble bees in a shopping center near Wilsonville to the application of a pesticide used to control aphids on some trees. Sometimes it takes dramatic and tragic events for us to fully understand how to walk more softly across the land. Xerces published a wonderful guide to conserving bumble bees entitled “Conserving Bumble Bees. Guidelines for Creating and Managing Habitat for America’s Declining Pollinators.” It is available for free on their website (www.xerces.org).
