All members of the genus Bombus, the world’s
roughly 250 bumblebee species are critical pollinators. In natural
ecosystems, bees are by far the most important pollinators of native plants,
and the insects are essential to producing more than a third of the
foods and beverages humans consume—an industry worth hundreds of billions of
dollars annually. Bumblebees are particularly major players: Because their
large bodies allow them to generate heat, the insects can fly earlier and later
in the day and in colder weather than most bee species, including honeybees.
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| Bumblebee on St. John's Wort |
How to Garden for Bumblebees
Bumblebees face many threats, ranging from pesticides
and disease to overgrazing, climate change and competition from European
honeybees. While individuals can do little to combat many of these problems,
anyone with a garden—no matter how large or small—can make a difference for
bumblebees that live nearby.
Here’s how to get started:
•
Provide pollen and nectar for food: Active
from early spring through late fall, bumblebees need access to a variety of
nectar- and pollen-producing flowers so food will be available throughout all
stages of the insects’ life. Bumblebees prefer flowers that are purple, blue or
yellow as well as perennial versus annual plants. To accommodate species with
varying tongue lengths, cultivate flowers of different sizes. Native plants are
best because they require less maintenance, rarely become invasive and have
coevolved with indigenous bumblebees. To see a list of native plant
recommendations for your region, go to www.xerces.org/lbj.
•
Ensure bumblebees have nesting sites: Unlike
the majority of native bees, bumblebees, like honeybees, are social insects
that live in colonies containing between 50 and 500 members. Most bumblebee
species nest underground, usually in abandoned holes created by ground
squirrels, mice or rats. Others nest aboveground in abandoned bird nests, grass
tussocks or cavities such as hollow logs or spaces beneath rocks. In gardens,
the insects make use of compost piles and unoccupied birdhouses. Having as many
of these habitat features as possible will help bumblebees, as will minimizing
practices such as mowing and tilling that destroy both nests and potential
future nest sites.
•
Provide overwintering habitat: In late
fall, bumblebee colonies die, leaving behind only new queens, which will
hibernate during winter and emerge the following spring to form new colonies.
Most queens overwinter in small holes just below or on the ground’s surface. In
yards and other human-dominated landscapes, they may seek shelter in sheds,
rock walls and woodpiles. Leaving leaf litter, downed wood and uncut bunch
grasses provides additional options. If you mow, do so with the mower blade set
at the highest safe level. When spring arrives, avoid raking or mowing until
April or May to protect hibernating queens.
•
Avoid or minimize pesticides:
Designed to kill insects, insecticides should be avoided, as should herbicides
that may kill the plants on which bumblebees depend. In cases where pesticides
cannot be avoided—to control a destructive invasive species, for example—The
Xerces Society recommends that you “choose targeted formulations with the
least-toxic ingredients, follow the manufacturer’s directions, apply the
pesticide as directly and locally as possible and apply when bumblebees are not
active (either after dark or during winter).” In addition, steer clear of
systemic pesticides (such as neonicotinoids, which are taken up by the vascular
systems of plants) and broad-spectrum pesticides (such as organophosphates and
pyrethroids). More information.
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