The Western Honey Bee, Apis mellifera, sustains its complex society through a diet sourced entirely from the plant world. This diet is collected, processed, and distributed to meet the energy and developmental needs of the entire colony. A successful hive relies on two main categories of plant resources: carbohydrates for fuel and proteins, fats, and micronutrients for growth. Worker bees convert these raw materials into storable food reserves, which is fundamental to the colony’s survival, particularly when natural forage is scarce.
Nectar: The Primary Energy Source
Nectar, a sugary liquid secreted by flowering plants, serves as the colony’s sole source of carbohydrates, powering flight muscles and regulating hive temperature. Foragers collect this liquid and store it in a specialized organ called the honey stomach for transport back to the hive. Nectar is highly variable but consists of 50 to 80 percent water, with the remainder being complex sugars, primarily sucrose.
Once a forager returns, she transfers the nectar to younger house bees, beginning the conversion into honey. This process involves adding digestive enzymes, notably invertase, which breaks down sucrose into simpler sugars like glucose and fructose. The nectar is deposited into honeycomb cells, and house bees rapidly reduce the moisture content from as high as 70 percent down to around 18 percent. This dehydration is achieved by fanning their wings over the open cells.
The resulting thick, low-moisture honey is a stable, long-term energy store. Bees cap the honey with beeswax for consumption during the winter months or times of nectar dearth.
Pollen: The Essential Protein Source
Pollen is the colony’s only natural source of protein, lipids, vitamins, and minerals. This nutrient-rich material is essential for the growth and development of new bees, particularly the larvae and young nurse bees. Foraging worker bees collect pollen, which adheres to their hairy bodies, and groom it into specialized structures on their hind legs called corbiculae, or pollen baskets.
The bees mix the collected pollen with nectar and glandular secretions to form compact pellets carried back to the hive. The pellets are packed tightly into honeycomb cells, tamped down, and covered with a layer of honey. This stored and processed material is known as “bee bread.” The addition of honey and enzymes initiates lactic acid fermentation, which preserves the pollen and makes the protein and other nutrients more digestible. Bee bread is consumed primarily by nurse bees, who use it to produce the specialized larval food.
Specialized Foods for Colony Development
The colony produces specialized foods within the hive that regulate the development and caste of its young. Royal Jelly is a creamy, protein-rich secretion produced by the hypopharyngeal and mandibular glands of young nurse bees. Royal Jelly is a complete food, containing protein, carbohydrates, lipids, and water, and it is fed to all female larvae for the first few days of their lives.
The developmental fate of a female larva is determined by the continuation of this diet. Larvae destined to become sterile worker bees are switched after about three days to worker jelly, a mixture of royal jelly, honey, and bee bread. In contrast, a larva that is to develop into a fertile queen is fed Royal Jelly exclusively throughout its entire larval stage. The diet switch introduces p-coumaric acid, which alters gene expression and pushes the larva down the worker development pathway.
Water and Supplemental Feeding
Water is a constant requirement for the colony, used year-round for several functions. Water foragers collect small amounts and bring it back to the hive to dilute thick stored honey, especially when it has crystallized, making it consumable. On hot days, bees spread water droplets throughout the hive, fanning them to create an evaporative cooling system that regulates the internal temperature.
Beekeepers sometimes intervene with supplemental feeding to ensure colony survival or stimulate population growth. When natural nectar is scarce, beekeepers provide sugar syrup, often a mixture of cane or beet sugar and water, to serve as a carbohydrate source. During times of pollen dearth, beekeepers may offer protein supplements, such as pollen patties. These patties are mixtures of natural pollen or a pollen-free substitute pressed into a digestible cake. These interventions are particularly useful in early spring to sustain brood rearing before natural forage becomes widely available.