The relationship between a bee and a flower is a classic example of mutual benefit in nature, where the needs of one organism are met by the actions of the other. The bee requires the flower’s resources for survival and colony maintenance, while the plant relies entirely on the bee for its own reproduction. Over millions of years, this interdependence has shaped the biology of both, leading to an intricate partnership that sustains ecosystems worldwide. This exchange encompasses specialized nutritional, structural, and reproductive necessities.
Nectar as the Primary Energy Source
Nectar is the sugary liquid secreted by flowers, serving as the bee’s primary source of carbohydrates and the fuel for all adult activities. This solution is composed of 70% to 80% water along with simple sugars, such as glucose, fructose, and sucrose. A foraging bee consumes some of the collected nectar immediately to power its flight muscles.
The majority of the gathered nectar is carried back to the hive in the bee’s honey stomach, where it begins the conversion process into honey. Hive bees repeatedly regurgitate and evaporate the liquid, reducing its water content to around 18% and adding enzymes that break down complex sugars into simpler forms. This concentrated honey is then stored to sustain the colony through periods when flowers are scarce, such as winter or during heavy rain.
Pollen for Brood Development
Pollen provides the protein, fats, vitamins, and minerals necessary for growth, development, and colony reproduction. Its nutritional composition is highly variable, with crude protein content ranging from 6% to over 30% depending on the plant species. Since no single pollen type provides all ten essential amino acids, bees must forage on a diverse array of flowers to ensure a balanced diet.
Pollen is moistened with nectar and packed into specialized structures on the bee’s hind legs, called corbiculae, before being transported to the nest. Inside the hive, nurse bees mix the pollen with nectar and glandular secretions to create “bee bread,” a fermented food source fed directly to the developing larvae. A single larva requires approximately 124–145 milligrams of this protein-rich food to complete its development into an adult worker bee.
Facilitating Plant Reproduction
While the bee’s motivation is purely nutritional, the flower’s purpose is to exploit this drive to achieve sexual reproduction through pollination. As the bee pushes into the flower to access the nectar or pollen reward, its hairy body brushes against the male anthers, collecting pollen grains. When the bee visits the next flower of the same species, this pollen is deposited onto the female stigma, fertilizing the plant.
This exchange is efficient due to co-evolution, where flowers have developed specific traits to attract bees and discourage other visitors. Many flowers display ultraviolet patterns, known as nectar guides, which are invisible to humans but direct the bee straight to the reproductive parts. Bees also display “floral constancy,” meaning a forager will consistently visit only one species of flower during a single trip. This behavior maximizes the likelihood of successful cross-pollination.
Other Floral Materials Used by Bees
Beyond the major food sources, flowers and plants offer other materials for hive construction and maintenance. Bees collect plant resins and gums, primarily from tree buds, which they mix with wax and salivary enzymes to create propolis. This sticky, antimicrobial material is used as a sealant to fill small gaps, sanitize internal surfaces, and protect the colony from pathogens.
Bees also collect water, sometimes found on petals or inside flowers, for hydration and temperature regulation within the nest. On hot days, bees spread water droplets inside the hive and use wing fanning to evaporate it, cooling the brood nest. Some specialized solitary bee species, such as those in the family Melittidae, collect floral oils from certain plants, using these lipids to line their brood cells or mix with pollen to feed their young.