🐝 How does a bee’s stinger keep stinging without the bee?

When a honeybee stings a mammal’s skin, its stinger remains attached. As it flies away, it also loses a small part of its abdomen. The stinger stays embedded. Researchers did not precisely understand how it continued to burrow in and inject venom without the bee controlling it.

An Australian team filmed this mechanism with very high-speed cameras. For the experiment, the researchers had the bees sting a transparent gel that reproduced some of the properties of skin. This allowed them to observe in detail what happens.

The stinger is not a simple needle. It consists of two pointed parts that slide against each other. They move forward in turn, latch onto the tissues and gradually pull the whole structure inward. The same movement also pushes out the venom contained in a small sac.

This is where the researchers discovered an astonishing trick. Each moving part carries a small flexible valve. As it moves forward, the valve unfolds and pushes the liquid, like a piston. When it moves backward, it folds up to let the venom pass through without bringing it back along.

Because the two valves work alternately, the venom can be pushed almost continuously. All of this takes place in a tiny space, without requiring the bee’s brain to control every movement.

To test their explanation, the researchers built an enlarged model of this system using 3D printing. They were able to reproduce the operation of this tiny pump and better understand how the valves deform during a cycle.

The study explains why a detached stinger remains active. It also shows why, in the event of a sting, it is useful to remove the stinger quickly when it remains in the skin: the venom sac and its mechanism can continue to work after the insect has flown away.

This natural pump could also interest engineers. They are seeking to design very small devices capable of moving liquids through medical instruments. The mechanism observed in bees could give them new ideas.