When a worker honey bee pulls away after stinging, the apparatus it leaves behind is not just a passive barb. The detached stinger can keep moving deeper and delivering venom on its own, a process called autotomy. A peer-reviewed study in PNAS has now shown how that tiny autonomous pump works.
Two pistons in one chamber
The roughly 2-millimeter stinger contains two sharp lancets that slide back and forth on interlocking rails. Each lancet carries a deformable valve inside a shared bulb chamber. The two sides move out of phase, so one advances while the other retracts.
On the downstroke, a valve expands and seals against the chamber, acting like a piston that pressurizes the venom. On the upstroke, it collapses so the chamber can refill. As the valves meet, their shape lets them squeeze past each other without interrupting the alternating cycle. The researchers found that this motion supports a continuous flow while potentially reducing backflow during refilling.