Bumblebees (genus Bombus) are large, fuzzy insects that play a foundational role in both wild ecosystems and agricultural food production. They are uniquely capable of “buzz pollination,” vibrating their flight muscles while on a flower to dislodge pollen, a technique essential for crops like tomatoes and blueberries. Unfortunately, many North American species have faced severe population declines, making public assistance in providing food, shelter, and safety a necessary conservation measure.
Cultivating Essential Food Sources
Ensuring a continuous supply of high-quality nectar and pollen is crucial for bumblebee survival. Bumblebees require a successive bloom schedule, meaning food must be available from the moment the overwintered queen emerges in early spring until the new queens hibernate in late autumn. Early spring sources are particularly important for the queen to establish her colony.
To maximize nutritional benefit, gardeners should prioritize planting native wildflowers, clover, and herbs like borage and lavender. Flowers with simple, single petals are better than complex, double-flowered hybrids. Horticultural breeding often converts the flower’s pollen-producing stamens into extra petals, reducing the available pollen. Additionally, the dense layers of petals on these hybrids can physically block the insect’s access to nectar and pollen reserves.
Planting late-season bloomers, such as goldenrod and asters, provides the final, energy-rich meals necessary for the new queens to prepare for winter hibernation. This focus on native and simple-structured flowers throughout the growing season provides the consistent fuel a colony needs to grow and successfully reproduce. Selecting plants that offer accessible rewards ensures the garden is a reliable foraging habitat.
Providing Safe Shelter and Nesting Sites
Bumblebees are cavity-nesting insects. Unlike honeybees, bumblebees favor small, enclosed areas, such as abandoned rodent burrows, dense tussocks of grass, or small voids beneath sheds. The queen searches for a dry, insulated space in the spring to begin laying her eggs.
Homeowners can easily create suitable habitat by adopting a less-tidy approach to landscape management. Leaving areas of the lawn unmown, allowing grass to grow into dense clumps, or tolerating patches of loose soil undisturbed can provide potential nesting locations. Small brush piles or stacks of old wood placed in a quiet corner of the yard also offer insulation and protection.
While commercially available bumblebee nesting boxes exist, their success rate is low, often showing occupancy rates below 10%. The most successful artificial sites mimic the natural, underground burrows bumblebees prefer, sometimes involving buried terracotta pots with an entrance tunnel. Preserving existing natural structures, like old rodent nests or dry, sheltered areas, is a more reliable way to support local colony establishment.
Minimizing Exposure to Harmful Chemicals
The widespread use of chemical pesticides threatens bumblebee health and survival. Systemic insecticides, particularly neonicotinoids, are dangerous because they are absorbed by the plant and contaminate the pollen and nectar bees consume. Even sublethal exposure to compounds like imidacloprid and clothianidin can severely impair the colony.
Sublethal exposure can lead to reduced foraging success, navigational problems, and a significant drop in reproductive output. Exposed colonies may produce up to 85% fewer new queens. Eliminating the use of these systemic products is the most direct action to ensure bumblebee safety.
For pest management, safer alternatives should be employed, such as manual removal of pests or introducing natural predators like ladybugs and lacewings. If an exhausted bee is found, an emergency intervention can be performed using a sugar-water solution. A simple mixture of two tablespoons of granulated white sugar dissolved in one tablespoon of water, offered on a small plate or spoon, provides a temporary energy boost to help the bee return to its nest. This emergency sugar solution should only be used as a one-off rescue, as it lacks the nutritional content of natural pollen and nectar.