How Honey Bees Breathe

Honey bees have no lungs or diaphragm, nor do they bring air in and out through the mouth…and there is no “nose” at all.  Instead, air is exchanged through a set of ten pairs of tiny “portholes” called spiracles – three pairs on the thorax and seven the abdomen. A bee contracts the abdomen to expel carbon dioxide through the spiracles, and as the abdomen relaxes, oxygen-rich fresh air is pulled in through the same openings (featured image: misfitanimals.com).

Six spiracles run down each side of the abdomen as shown; another pair is tucked within the sting chamber (Image: abejas.org)

Fresh air flows into the trunk of the trachea and continues through a system of branching tracheal tubes that connect to thin-walled sections that form air sacs (atria) for temporary storage. From these atria, it travels through branches of smaller dimensions (tracheoles) to carry oxygen to all parts of the body. There are various sizes of these sacs that serve the head, thorax, abdomen, and legs.

Changing the air pressure in the atria helps to move oxygen to wherever it is needed, and waves of muscle contractions from top to bottom or from front to back of the abdomen control the flow of air in and out of the sacs.  To maintain the necessary air pressure in this system, every spiracle has a valve that shuts tightly between “breaths” of air in and out, preventing backflow.

Honey bee tracheal system (adapted from NOPBA “The Swarm,” Summer 2020.

This type of respiratory system transports oxygen directly to the tissues and removes carbon dioxide without binding and carrying the gases within a blood-like liquid, as is required in mammalian systems.

That is, the fluid called “hemolymph” in bees and other arthropods does not carry gases, but rather, it is a liquid system that distributes nutrients throughout the body, along with components that confer immunity and defense against invading microorganisms.

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