Bumblebees are a diverse group of over 250 species of fuzzy, winged insects that play a significant role in ecosystems and agriculture. They are recognized as important pollinators for various plants, including vegetables, fruits, oilseeds, legumes, and fodder crops. Their activity supports the reproduction of wildflowers and contributes to the success of many cultivated plants. Maintaining healthy bumblebee populations is beneficial for the environment.
What Flowers Attract Bumblebees
Bumblebees are drawn to flowers exhibiting specific characteristics related to color, shape, scent, and the presence of abundant nectar and pollen. Bees perceive color differently than humans, with their vision extending into the ultraviolet spectrum. Bumblebees are particularly attracted to flowers in the blue, purple, and white ranges, often seeing ultraviolet patterns that guide them toward nectar sources. These patterns attract bees, even if the flower’s visible color is not blue.
The shape of a flower also influences its appeal to bumblebees, which possess varied tongue lengths among different species. Long-tongued bumblebees are well-suited for deep, tubular flowers like honeysuckle and foxglove, as their proboscis can extend to reach hidden nectar. Conversely, short-tongued species often prefer flowers with shorter corollas or open, dish-shaped structures. Some short-tongued bumblebees use a method called “nectar robbing,” where they bite holes in the flower to access nectar without proper pollination.
Beyond visual cues, floral scent plays a role in attracting bumblebees, with fragrances often released during the day when these pollinators are most active. The presence of nectar, a sugar-rich liquid providing energy, and pollen, a source of protein and lipids, are direct incentives for bumblebee visits. Bumblebees can detect the nutritional quality of pollen and show a preference for pollen with higher protein-to-lipid ratios, optimizing their foraging efforts for colony health.
How Bumblebees Pollinate Flowers
Bumblebees employ specialized methods to gather pollen and nectar, which directly facilitates the pollination process. One distinctive technique is “buzz pollination,” which is used for plants where pollen is tightly held within tubular anthers. The bumblebee grasps the flower’s pollen-producing structures with its mandibles and vibrates its flight muscles rapidly, causing the flower and anthers to shake and dislodge pollen. This vibration effectively releases pollen from plants such as tomatoes, potatoes, and blueberries.
The bee’s hairy body is well-suited for collecting pollen, as the branched individual hairs increase surface area and make pollen grains stickier. As the bumblebee moves within and between flowers, pollen adheres to these hairs and is then transferred to the stigma of other flowers, enabling plant reproduction. Bumblebees also utilize their long, hairy tongues, or proboscis, to lap up nectar from deep within flowers. This proboscis can extend and retract, acting like a straw to draw nectar through capillary action.
When not in use, the bumblebee’s proboscis is folded neatly under its head and body. This efficient collection and transfer of pollen, combined with their ability to forage in cooler, wetter, or windier conditions than some other bees, makes bumblebees highly effective pollinators. Their robust nature allows them to open closed flowers, such as snapdragons, to access nectar and pollen.
Cultivating a Bumblebee Garden
Creating a garden that supports bumblebees involves strategic planting and mindful garden management practices. A diverse selection of native flowering plants is recommended, as these have co-evolved with local insect populations and are well-adapted to regional conditions. It is beneficial to choose plants that offer a continuous succession of blooms from early spring through late autumn, ensuring a steady supply of nectar and pollen throughout the bumblebee’s active season. This continuous food source is important for the entire colony lifecycle.
Avoiding the use of pesticides is a significant step in protecting bumblebees and other pollinators. Neonicotinoid insecticides, for instance, can be absorbed into plant tissues, including nectar and pollen, harming bees even at low concentrations. When purchasing plants, it is advisable to inquire whether they have been treated with such chemicals, or to consider growing plants from untreated seeds or cuttings. Opting for native plant varieties over some showy horticultural hybrids is also suggested, as the benefits of hybrids for pollinators are not always clear.
Providing suitable nesting and overwintering sites is another aspect of cultivating a bumblebee-friendly garden. Many bumblebee species nest underground in abandoned rodent burrows or other cavities, typically one to four feet deep. Leaving undisturbed areas in the garden, such as tussocky grass or old plant debris, can offer potential nesting spots. Queens often hibernate underground, so maintaining areas of loose, well-drained soil in sunny locations can provide safe overwintering sites.