One common sight is a bee rubbing its back legs together while perched on a flower or inside its hive. This action is part of complex routines fundamental to a bee’s survival and colony well-being. These rhythmic leg movements serve multiple purposes, from efficient food collection to maintaining personal hygiene.
Gathering and Transporting Pollen
Bees primarily rub their back legs together to manage the pollen they collect. As a bee forages, its fuzzy body hairs accumulate pollen grains. The bee then systematically brushes this pollen from its body and other legs towards its hind legs. On the hind legs of female worker bees, specialized structures facilitate the packing and transport of pollen.
The collected pollen is moistened with nectar or saliva, forming a sticky pellet. This mixture is then pressed into a concave area on the outer surface of the hind tibia, known as the corbicula, or pollen basket. Each hind leg carries one such pollen pellet, which can collectively weigh a significant portion of the bee’s body weight. This efficient packing allows the bee to carry substantial loads back to the hive, where the pollen serves as a vital food source.
Keeping Clean and Sensory Sharp
Leg rubbing is also a crucial part of a bee’s grooming routine. Bees use their legs to meticulously clean their antennae, eyes, and other body parts. Pollen, dust, and other debris can accumulate on a bee’s body, particularly on its sensitive antennae and compound eyes. Keeping these sensory organs clear is important for navigation, communication, and detecting food sources.
The forelegs are equipped with specific tools, such as an antennae cleaner, to remove particles from these areas. After cleaning, the debris and excess pollen are often transferred to the hind legs, contributing to the material gathered there. This self-grooming, known as autogrooming, is complemented by allogrooming, where bees clean their nestmates, further ensuring the colony’s overall cleanliness and health. Grooming also helps in removing external parasites, like Varroa mites, which can threaten individual bees and the entire hive.
The Anatomy Behind the Action
The specialized anatomy of a bee’s legs enables these complex actions. Honey bees have three pairs of legs, each adapted for different tasks. The front legs possess an antennae cleaner, which is a notch with a comb-like row of stiff hairs used to clean the antennae. The middle legs help in transferring pollen from the front legs to the hind legs and assist in cleaning the thorax.
The hind legs are notably modified for pollen handling. They feature a “pollen comb,” a row of stiff hairs on the basitarsus, used to scrape pollen from the bee’s body and other legs. Adjacent to this is the “pollen press,” a mechanism that compresses the loose pollen into a dense pellet. Finally, the “corbicula,” or pollen basket, is a polished, concave area on the outer surface of the tibia, surrounded by long, curved hairs that hold the pollen pellet securely during flight.
Critical for Bee and Colony Health
The leg-rubbing behaviors are fundamental for the individual bee and the collective health of the colony. Efficient pollen collection ensures a steady supply of protein, lipids, vitamins, and minerals for the entire hive. Pollen is especially important for feeding developing larvae and young nurse bees, which require it to produce royal jelly. A colony can require a significant amount of pollen annually, ranging from 15 to 55 kg.
Grooming behaviors, both self-directed and social, are important for preventing disease and removing parasites. By keeping themselves and their nestmates clean, bees reduce the spread of pathogens and mites, which can otherwise weaken or destroy a colony. These actions collectively contribute to the hive’s productivity, resilience, and overall survival.