The relationship between a bee and a flower is a highly evolved partnership, where the flower receives the benefit of pollination and the bee gains sustenance. A bee’s “favorite” flower is not random, but a precise calculation of energy expenditure versus nutritional reward. This preference is driven by evolutionary necessity, favoring flowers that offer the clearest signals and the most abundant, highest-quality resources. Understanding these choices requires looking closely at the sensory world of the bee and the chemistry of the floral rewards.
How Bees Choose a Flower
Bees use a complex, multi-sensory system to locate and select the most rewarding flowers, relying on visual, olfactory, and morphological cues. A flower’s color is a primary signal, but bees perceive the spectrum differently from humans, seeing blue, violet, and ultraviolet (UV) light especially well. Red flowers often appear black to them, while yellow and blue hues stand out brilliantly. Many flowers have UV patterns, invisible to the human eye, that act as “nectar guides,” directing the bee toward the reproductive parts of the plant where the pollen and nectar are located.
Floral scent is a powerful long-distance beacon, allowing bees to detect potential food sources before they are close enough to see them. Flowers emit volatile organic compounds that create a unique scent profile, which bees learn to associate with a reward. Researchers have found that bees can even distinguish flowers based on the pattern of scent distribution across the petals. The physical structure of the flower also influences a bee’s choice, with size and shape determining accessibility. Different bee species, such as long-tongued bumblebees versus short-tongued solitary bees, have co-evolved with specific flower morphologies, preferring shapes that match their feeding apparatus for efficient foraging.
The Nutritional Value of High-Yield Flowers
A flower is considered “high-yield” when it offers a significant quantity and quality of the two main resources bees require: nectar and pollen. Nectar serves as the primary energy source for adult bees, fueling their flight muscles with simple sugars like glucose, fructose, and sucrose. The concentration of these sugars is a major factor in a bee’s choice, as higher-concentration nectar provides a more efficient energy return on the foraging trip.
Pollen is the bee’s source of protein, lipids, vitamins, and minerals, which are essential for larval development and hive health. The nutritional quality of pollen varies widely among plant species, with crude protein content ranging from approximately 6% to 30% of the dry weight. Bees thrive on pollen that contains a complete profile of the ten amino acids essential to their diet.
A single type of pollen rarely provides all the necessary nutrients, which explains why bees seek a varied diet, preferring plants that offer diverse, high-quality pollen. Flowers that produce ample amounts of both high-sugar nectar and nutrient-dense pollen are the most attractive and valuable to a foraging bee. High-lipid content in pollen is also attractive, providing necessary fats for bee health. The overall abundance of flowers in a patch also plays a role, as bees often select the nearest field of equally rewarding flowers to conserve energy.
Creating an Optimal Bee Habitat
Translating the science of bee preference into practical action means focusing on providing continuous, high-quality forage and safe nesting sites. Planting native species is highly effective because they have co-evolved with local bee populations, ensuring their bloom times and flower structures are suited to the needs of regional pollinators. An optimal habitat must offer a succession of blooms, providing food from early spring through late fall so that bees have a constant supply of resources.
To support the greatest diversity of bees, it is helpful to plant a variety of flower shapes, sizes, and colors, including species that attract both generalist and specialist foragers. Protecting bees requires minimizing the use of chemical treatments. Insecticides, herbicides, and fungicides can all harm non-target species like bees, either by direct contact or by eliminating the flowers they rely upon for food. Providing nesting habitat is essential, which means leaving small patches of bare, untilled soil for ground-nesting solitary bees, or leaving dead wood and snags for cavity-nesting bees.