Honeybee larvae represent a foundational stage in the development of a bee colony. These small, grub-like creatures are the future workforce and reproductive capacity of the hive. They develop within hexagonal wax cells, completely dependent on adult worker bees for their sustenance and care. The health and abundance of larvae directly reflect the overall well-being and growth potential of the honeybee colony. Without healthy larvae, a hive cannot sustain its population or functions.
The Larval Life Cycle
The journey of a honeybee begins as an egg, laid by the queen at the bottom of a wax cell. After about three days, the egg hatches into a tiny, white, legless larva. This larval stage is focused on rapid growth and feeding.
Larvae undergo a series of molts, shedding their skin as they increase in size. Each stage between molts is called an instar. As they grow, their appearance changes from a small, C-shaped grub to a larger, more elongated form that nearly fills the cell. This period of intense eating and growth lasts about six days for worker and drone larvae, and slightly less for queen larvae.
Once the larva has completed its growth, it spins a cocoon around itself within the cell. Worker bees then cap the cell with wax, marking the transition from the larval stage to the pupal stage. Inside this sealed cell, the bee undergoes metamorphosis.
Nurturing and Nutrition
Nurse bees, which are young worker bees, play a dedicated role in feeding and caring for the developing larvae. Their brood food glands mature after consuming large amounts of bee bread, which is fermented pollen. This allows them to secrete the necessary food for the young.
All newly hatched larvae receive royal jelly for their first few days, a highly nutritious substance secreted from the hypopharyngeal and mandibular glands of nurse bees. This initial feeding provides a strong start for all developing bees. After this initial period, the diet diverges based on the larva’s destiny.
Worker and drone larvae are primarily fed a mixture of royal jelly, pollen, and honey. This diet provides the necessary proteins, vitamins, and carbohydrates for their development. Queen larvae, however, receive an exclusive and continuous diet of royal jelly throughout their entire larval stage.
Nurse bees make thousands of visits to individual brood cells during the larval stage, ensuring a constant supply of food. This intensive feeding regimen is known as progressive feeding.
How Castes Are Determined
The differentiation of honeybee larvae into queens, workers, or drones is primarily influenced by two factors: the type of cell in which the egg is laid and the diet provided. The queen bee strategically lays fertilized eggs in smaller, hexagonal worker cells, or unfertilized eggs in slightly larger drone cells. For a future queen, a specially constructed, larger queen cell is used.
Female larvae, developing from fertilized eggs, have the potential to become either workers or queens. The determining factor is their diet. Larvae destined to become worker bees receive royal jelly for a few days, followed by the bee bread mixture of pollen and honey. This diet limits their development, resulting in sterile female worker bees.
Conversely, female larvae selected to become queens are continuously fed large quantities of royal jelly throughout their entire larval development. This nutrient-rich diet triggers the full development of their reproductive organs and larger body size, enabling them to become fertile queens. This specialized diet is the sole reason female larvae develop into reproductive queens instead of workers.
Male drones develop from unfertilized eggs laid in larger drone cells. Their diet consists of a blend of pollen and honey, similar to worker larvae, but the larger cell size accommodates their larger body. The combination of egg fertilization status, cell size, and diet precisely dictates the caste outcome for each honeybee larva.
Threats to Larval Health
Honeybee larvae are susceptible to various diseases and pests that can severely impact the colony’s health and productivity. American Foulbrood (AFB), caused by the bacterium Paenibacillus larvae, is a serious disease. Infected larvae die after their cells are capped, turning into a dark, gluey mass with a characteristic foul odor. This bacterium forms resilient spores that can remain viable for decades, making it difficult to eradicate.
European Foulbrood (EFB), caused by the bacterium Melissococcus plutonius, primarily affects young larvae before capping. Infected larvae appear twisted in their cells, turning yellowish-brown and eventually dying. Unlike AFB, EFB does not form spores that persist indefinitely, but it still weakens colonies by reducing the emerging workforce. Both foulbroods are highly contagious within the hive and between colonies.
Chalkbrood, caused by the fungus Ascosphaera apis, affects larvae that are chilled or stressed. Infected larvae become hard, chalk-like mummies, ranging in color from white to black. Nurse bees often remove these mummies from the hive, but severe infections can significantly reduce the number of healthy developing bees. This fungal disease thrives in damp conditions.
Parasitic mites, particularly Varroa destructor, pose a significant threat to larval and pupal health. Female Varroa mites enter capped brood cells and reproduce, feeding on the hemolymph (blood) of the developing larvae and pupae. This feeding weakens the bees, impairs their development, and can transmit various viruses, leading to deformed wings, reduced lifespan, and overall colony decline. High mite infestations can harm a colony by depleting its future generations.