Pollinator Profile- bumblebees!


In the Pacific Northwest there are over a dozen different species of bumble bees, close to 50 in North America and over 250 species world-wide. Bumble bees are members of the Apidae family which also includes honey bees and carpenter bees. In the Pacific Northwest they vary in color, some with red, white, pale yellow, and orange, but the most familiar are black and yellow.

The various species are gentle and unlikely to sting unless their nests are disturbed, in which case they can defend their nests aggressively. Like the honey bee, they are social insects and nests contain many individuals. Unlike the honey bee, bumble bees nests are annual, meaning the nest dies off each year. They are large and very hairy and the females carry pollen moistened by nectar in their baskets, which are structures on their hind legs that fill with pollen, but not easily seen when empty.

They are some of the earliest bees to emerge in the spring and stay around the longest, often the last to be seen into the fall. Bumble bees can regulate their own body temperature by shivering or basking in the sun. This enables them not only to stay active longer during the season, but also during wet or cooler weather. They visit a variety of flowers throughout the season and as such require many different plants that bloom during the full season. They are also important pollinators of a wide range of crops such as watermelon, tomatoes and blueberries.

In the spring new queens emerge from their migration in search of a new place to build a nest. They nest socially with one queen starting her own colony.  The queen will produce an initial batch of worker bees to take over the foraging at which point she will start laying eggs around wax pots she creates to hold pollen and nectar. Near the end of the season the queen will produce a few males which will leave the nest to find mates and not return. At this time she also produces new queens. At the end of the summer nearly all of the colony will die, including the old queen, leaving only a few queens who will leave to mate before hibernating and starting new colonies the following spring. The new queens hibernate underground by digging several inches under either soil or leaf litter.

Bumble bees will make use of a wide range of nesting places including under dead wood, in a tree cavity, in old nests from birds or mice or man-made boxes or shelters. In an urban environment they will also nest in building walls, bird houses, rock walls and other urban debris. The basic requirements for built bumble bee nests are a supply of dry insulation materials and an undisturbed area. See Landscaping for Wildlife in the Pacific Northwest or Attracting Native Pollinators: The Xerces Society Guide to Conserving North American Bees and Butterflies and Their Habitat. It’s best to locate them away from people and activity where they won’t be disturbed unnecessarily and there’s less risk of seeming like a threat to them.

There are many common and native plants that will attract bumble bees. Because they are large, they will forage as far as a mile or more away from their nest location. Plants they prefer include those listed below as well as Bee Balm, Blackberry, Blueberry, Fireweed, Goldenrod, Huckleberry, Phacelia, Salal, Spirea.

For more information about bumble bees visit The Metropolitan Field Guide.