Bees and flowering plants have a mutually beneficial relationship foundational to global ecosystems. Flowers offer rewards to encourage the insect visitors necessary for pollination. Bees collect two distinct substances from flowers: nectar, which provides the colony’s energy, and pollen, which serves as its source of protein and other building blocks. These are the sole basis of the bee diet, and each is processed for a specific function within the hive.
Nectar: The Primary Fuel for Adult Bees
Nectar is a sugary fluid, primarily a solution of carbohydrates, that a flower produces to attract pollinators. When a foraging bee extracts this liquid, it is typically high in water content, often around 80%, with the sugar being mostly sucrose. The bee stores the collected nectar in a specialized internal pouch called the honey sac or crop, which is distinct from its digestive stomach.
During the flight back to the hive, the process of conversion begins as the bee secretes enzymes, such as invertase, into the nectar. This enzyme breaks down the complex sugar sucrose into the simpler monosaccharides, glucose and fructose. Once deposited into the honeycomb cells, “house” bees continue this enzymatic process and begin the physical transformation.
The bees use rapid wing movements to create air currents across the open cells, which evaporates the excess water from the high-moisture nectar. This dehydration concentrates the sugars, reducing the water content from the initial 80% down to a stable range of 17% to 20%. This final, concentrated product is honey, a stable, energy-dense food source that provides adult bees with fuel for flight, generating heat, and overall colony maintenance.
Pollen: Essential Nutrition for Brood Development
Pollen grains are the male reproductive cells of a flower and, for the bee colony, they represent the primary source of protein, lipids, vitamins, and minerals. This protein is essential for the growth of developing larvae, collectively known as the brood, and for the young nurse bees who care for them. Nurse bees must consume large amounts of pollen to develop the specialized glands required to produce royal jelly, the protein-rich food fed to the youngest larvae.
Once collected and brought back to the hive, the raw pollen is mixed with small amounts of nectar or honey and bee saliva, then tightly packed into honeycomb cells. This mixture is known as “bee bread” and undergoes a natural anaerobic lactic fermentation process. The fermentation breaks down the hard outer shell of the pollen grain and converts complex nutrients into more readily digestible forms, significantly increasing the nutritional availability for the bees.
Pollen’s nutritional composition is highly variable depending on the floral source, but colonies require a diet that averages a crude protein level between 20% and 25% for optimal health and brood rearing. The resulting bee bread is stored near the brood nest and serves as the colony’s long-term protein reserve, ensuring that all life stages have access to the necessary amino acids for growth and development.
Specialized Tools for Gathering and Transport
Bees have evolved specialized anatomical structures to efficiently collect and transport these two distinct food sources. For gathering nectar, the bee employs its proboscis, a long, flexible, straw-like mouthpart that is extended deep into the flower to reach the sugary fluid. The proboscis functions like a drinking straw, drawing the liquid up and into the internal honey sac for transport back to the hive.
Pollen collection relies on a different set of tools, beginning with the bee’s entire body covered in branched hairs that easily snag the tiny grains. An intriguing physical factor is the electrostatic charge a bee develops while flying, which helps pollen grains adhere to its body, much like static cling. The bee then meticulously brushes the grains off its body and packs them onto a specialized structure on its hind legs called the corbicula, or pollen basket. This concave area is surrounded by stiff hairs that secure the pollen pellet, allowing the bee to carry a substantial load back to the colony.