Anatomy of the honey bee – Apis mellifera

The honey bee -
Class – insect

Order – Hymenoptera

Family – Apidae

Genus – Apis

Species - mellifera

Honey bee castes

Queen	Worker	Drone

Note the QUEEN is large with a long tapered abdomen and the wings are shorter than the body. The queen lays fertilized eggs – workers and unfertilized eggs – drones.

The DRONE is a male they have no sting. The eyes cover most of their head and the wings are as long as their bodies. They have a blunt tipped stocky abdomen.

External anatomy

The figure illustrates the basic surface anatomy of the honey bee – Apis mellifera. Note the size difference and slight shape differences between the queen, worker and drone. Especially note the large eyes of the drone – useful in the mating flight.

Internal general anatomy of a honey bee

Photograph of the digestive tract of the bee (with the head end removed)

Pheromones glands

The bee contains several glands.

Nasanov gland

This produces a variety of chemicals which the bee uses to assist identification of the entrance of the hive.

Koschevnikov gland

This releases alarm pheromone – attracts other bees to attack and sting the same part of the body of the offending animal. Several compounds – principle one is isopentyl acetate.

In the queen this gland products are responsible for the formation of the clusters of court bees that surround the queen.

Dufour’s gland

The products of this gland line the entrance to the hive and may assist recognition of family or nest ownership

Mandibular glands

In young workers this gland produces the lipid-rich white substance mixed with the hyopharyngeal gland secretions resulting in royal jelly.

In older worker this produces part of the alarm pheromone.

In the queen, this gland has a number of important functions – produces queen substance (queen mandibular substance) and is associated with:

Suppression of construction of emergency queen cells

Inhibits ovary development in the workers

Attracting drones during the mating flight

Attracts the attendant workers

In the drone, the mandibular gland assists in the formation of drone gatherings – in drone congregation areas (DCA’s) which appear in open fields.

Hypopharyngeal glands

Produce protein-rich sections (Royal jelly) when the worker is a nurse bee.

When the worker becomes a forage bee it produces invertase which helps break down sucrose into fructose and glucose.

Pre-tarsus gland

As yet its function is not known.

Arnhart or footprint glands on each foot

The reproductive organs

Worker reproductive organs

	The female worker reproductive tract Which in the worker develops in the stinging gland. Note the stinger has two components, the poison gland (filled with colourless liquid when fresh) and the alkaline gland (which may appear yellow) together with the stinger. Each sting contains 150 mg of venom. Note bees, unlike wasps, die after using the stinger as the organ is left in the victim.
Queen reproductive organs
The queen reproductive tract. A single ovariole		During the mating flight the queen the drone’s penis bulb is discharged by eversion of the penis into the queen’s vaginal pouch. After mating the queen separates from the drone and the male penis bulb remains in the female. The organ is torn from the male at the penis neck. The queen may mate with several drones during the flight. The spermatozoa are discharged in the distended lateral oviducts. Once back at the hive, the workers remove the penis bulb from the queen. The spermatozoa are then moved into the vagina and then the spermatheca gland where they remain for the productive life of the queen – up to 5 years. If the queen “runs out of semen” she will only lay unfertilized drone eggs.

The abdomen on the queen bee – concentrating on the reproductive organs

Male reproductive tract

During mating, sperm mass stored in the bulb of penis is discharged by eversion into the queen’s vagina. After mating the queen separates from the male with the bulb of penis remaining in her genital tract. The male reproductive organs tear at the penis neck. The drone subsequently bleeds to death.

The male abdomen with the penis everted	End of the male abdomen, ventral aspect

Head of the honey bee – note all activities in the hive are in complete darkness

All communication is done by touch, feel and smell

The mouth parts are combined so they can chew and suck having both proboscis and mandible. Many insects have evolved to possess only one or the other capabilities.

General anatomy of the front of the head	Caudal view from the thoracic inlet
Mouth parts extended from head	Dissected rostal mouth parts
Head dorsal view showing ocelli

Eyes

The honey bee has two sets of eyes: Ocelli – three simple eyes found near the top of the bee’s head. Provide information regarding light intensity. Compound eyes – these are very large in the male drone for enhanced vision during the mating flight.

The compound eye made from individual ommatidia. Note bees eyes are the correct way round with the nerve cells behind the light collection cells – unlike vertebrates

A cross-section through a single ommatidia

Occasionally drones will be born with white eyes. This is a genetic defect. Replace the queen.

Thorax of the honey bee

Unlike other insects the bee’s thorax is divided into four segments – prothorax, mesothorax, metathorax and propodeum. The prothorax carry the prothoracic legs. The mesothorax and metathorax also carry legs and each of the wings. The claws on the last tarsomere allows bees to walk on rough surfaces (tree trunks) together with a soft pad (arolium) allowing them to walk on smooth surfaces (leaves) The hind legs in the worker are fringed with long, curved hairs and the space thus enclosed is called the pollen basket or corbicula.

Prothoracic leg Lateral view	Prothoracic leg medial view
Detail of the prothoracic antennae cleaner	Detail of the mesothoracic wax spine
Mesothoracic lateral view	Mesothoracic medial view
Metathoracic lateral view	Metathoracic medical view

Tarsus of the mesothoracic leg

Tracheal system in the thorax

The gross appearance of the tracheal system in the thorax	With the prothorax tergite removed
Detail of the main tracheal duct	Examination of the normal trachea by the microscope

Wings

The development of the wing is a fascinating story of insect evolution. One possibility are that their origins start as gills.

Detail of the forewing limb	Detail of the hamuli – wing hooks