Bumble bees are industrious pollinators crucial for the reproduction of many wildflowers and food crops. They possess a unique ability known as “buzz pollination,” where they vibrate their flight muscles to release pollen trapped within certain flowers, making them highly effective. Understanding their specific needs for food, shelter, and safety allows you to transform your yard into a supportive environment. These steps will help you attract and sustain healthy bumble bee populations.
Planting the Right Flowers for Foraging
The primary method for attracting bumble bees is ensuring a continuous and diverse supply of nectar and pollen from early spring through late fall. They prefer native plants because these species have co-evolved with local bees, offering the most nutritionally complete food sources. Prioritizing native wildflowers, herbs, and flowering shrubs creates a robust forage landscape throughout the entire growing season.
Bumble bees often favor flowers with a tubular shape and a purple, blue, or yellow coloration, which their vision is best suited to detect. Their long tongues and large bodies make them effective at reaching nectar deep inside blossoms like Bee Balm (Monarda) and Foxglove Beardtongue (Penstemon). Providing a succession of blooms is important to support the colony cycle, beginning with queens emerging in spring and ending with new queens fattening up for hibernation in the fall.
Early-season sources like chives, dandelions, and native clovers provide the queen with the energy needed to establish her nest. Throughout the summer, plants such as sunflowers and coneflowers offer abundant resources for the growing worker population. Later in the season, goldenrods and asters supply the final energy reserves for the new queens before they enter winter dormancy.
Providing Safe Habitat and Nesting Locations
Bumble bees are social insects that form annual colonies, utilizing existing cavities for nesting rather than creating a permanent hive. The queen typically seeks out a sheltered, insulated space, with abandoned rodent burrows being a common and highly successful natural choice. They may also establish their nests in dense clumps of grass, under tussocks, within compost piles, or beneath rocks and hollow logs.
Gardeners can provide suitable nesting areas by leaving certain sections of the lawn unmowed, allowing grass to grow thick for natural cover. Building or maintaining a brush pile or a slightly open compost heap in a quiet corner offers excellent insulation and potential nesting material. While artificial bumble bee boxes are sold, they often have a low colonization success rate, making the creation of natural, undisturbed habitat a more reliable approach.
Hibernation sites are necessary for the new queens to survive the winter and start new colonies the following spring. Queens will burrow into loose, well-drained soil, often at a depth exceeding 10 centimeters, or hide within leaf litter and beneath log piles. Delaying fall garden cleanup, particularly raking or tilling, until spring helps protect these overwintering queens from accidental disturbance.
Eliminating Threats from Pesticides and Chemicals
The presence of insecticides is a threat to bumble bees, with systemic chemicals posing a long-term danger to the colony’s health. Neonicotinoids, in particular, are absorbed by the plant and translocated to the nectar and pollen, making the entire plant toxic to foraging bees. Exposure to even sublethal doses of these compounds can impair a worker bee’s ability to navigate, reduce its food consumption, and inhibit the queen’s brood production capacity.
Systemic products applied to woody plants can remain present in the blossoms for over a year, meaning that treated trees or shrubs should be avoided entirely. When purchasing nursery plants, inquire about their treatment history to avoid introducing plants pre-treated with systemic pesticides. For unavoidable pest problems, non-chemical alternatives, such as manual removal or introducing beneficial predatory insects, should be the first choice.
If a conventional insecticide must be used, applying it in the late evening, after the bees have ceased foraging for the day, can reduce direct contact exposure. Avoid spraying any chemicals, even those labeled as “bee-safe,” directly onto open flowers or plants in full bloom where bees are actively collecting resources. The safest action is to eliminate all use of broad-spectrum and systemic insecticides within the garden environment.