Bees sustain themselves and their complex societies through a diet derived entirely from flowering plants, a nutritional dependency that drives their global importance as pollinators. The food they collect is not only fuel for the adult bee but also the raw material for highly specialized, manufactured products that determine the fate and function of every member of the colony. This plant-based diet, consisting primarily of nectar and pollen, is meticulously processed and allocated to ensure the survival and reproductive success of the entire social structure.
The Primary Fuel: Nectar and Honey
The carbohydrate source for bees is nectar, a sugar-rich liquid secreted by flowers. Nectar concentration can vary significantly, ranging from as low as 4% to over 60% sugar, but it is primarily composed of sucrose, glucose, and fructose. Foraging bees collect this liquid and store it in a specialized organ called the honey crop for transport back to the hive.
Once inside the colony, receiver bees convert the thin nectar into dense, storable honey. They mix the nectar with enzymes, notably invertase, which breaks down the sucrose into the simpler sugars, glucose and fructose. The bees then vigorously evaporate the water content, often reducing it from around 70% down to 16% to 20%, by fanning it with their wings. This dehydration process, combined with the slightly acidic nature of the final product, prevents microbial growth and allows honey to function as the colony’s long-term energy storage.
The Building Blocks: Pollen and Brood Food
While carbohydrates fuel adult activity, pollen provides the necessary proteins, fats, and micronutrients for colony growth and development. Pollen is the bees’ sole source of protein, required for the development of body tissue, muscles, and the glands used to secrete manufactured foods. Foragers collect pollen, sometimes carrying it back to the hive in specialized structures on their hind legs known as pollen baskets.
Upon arrival, the collected pollen is mixed with nectar or honey and glandular secretions containing enzymes, then tightly packed into honeycomb cells. This mixture undergoes a natural fermentation process, primarily driven by lactic acid bacteria, which transforms it into a highly digestible product called “bee bread.” The fermentation softens the tough cellulose shell of the pollen grains, which makes the proteins and other nutrients more bioavailable. Bee bread is the protein-rich food used to feed the developing larvae.
Specialized Nutrition for Colony Roles
The honey bee colony’s survival depends on a diet differentiated based on the individual bee’s role and developmental stage. Nurse bees, young workers aged six to twelve days, consume large amounts of pollen to activate their hypopharyngeal and mandibular glands, which secrete a protein-rich substance known as royal jelly. This milky, white substance is fed to all larvae—worker, drone, and queen—for the first three days of their lives.
Royal jelly, which is composed of water, sugars, and a high concentration of proteins including the Major Royal Jelly Proteins (MRJPs), is the determining factor in caste development. Worker and drone larvae are switched to a diet of bee bread and honey after three days, but a larva destined to become a queen is continuously fed copious amounts of royal jelly. This specialized, sustained diet triggers the morphological development necessary for a fertile queen. Adult drones are fed by worker bees and require a protein-rich diet, often consisting of bee bread, to support their physical development until mating flights.
Not All Bees Eat Alike
The intricate systems of food processing and storage observed in honey bees are specific to their highly social organization. The majority of the world’s bees are solitary or have much smaller, less-organized colonies, which dictates a simpler, more direct feeding strategy. Solitary bees, such as mason bees or leafcutter bees, do not produce honey or royal jelly, nor do they rely on complex, manufactured foods.
Instead, a solitary female provisions a nest cell with a mass of raw pollen and nectar, known as a pollen loaf, which she seals with a single egg. The larva hatches and feeds directly on this unprocessed mixture for its development. Similarly, social species like bumble bees, which form smaller, annual colonies, rely on direct consumption of nectar for energy and pollen for protein, storing small amounts of honey and unprocessed pollen for immediate needs. These bees maintain a direct link between the floral resources and the brood’s diet, lacking the complex food allocation systems of the honey bee.