If you've ever grimaced after being stung, new footage might make you wince even more.

Scientists have captured the hidden mechanics of a honey bee's sting in astonishing detail, revealing that the tiny needle left behind continues attacking long after the insect has flown away.

Using high-speed cameras, Australian researchers filmed a detached stinger pumping venom into a gel designed to mimic human skin.

The footage shows the needle steadily working its way deeper into the target under its own power.

Close observations also revealed the 2mm-long structure functions as a sophisticated double-piston micro-pump.

‘We’ve known since as early as 1910 that the venom sac of a honey bee stinger empties into a chamber with little pumping elements called valves, but until now we didn’t know exactly how they work,’ lead author Dr Fiorella Ramirez-Esquivel, from Macquarie University, explained.

‘If you've ever been stung by a bee, you'll know it's a very painful process, but now we’ve been able to identify all the working parts packed into the tiny stinger.’

After a worker bee stings, it leaves the barbed stinger behind in the skin in a process known as autotomy.

Rather than becoming harmless, the abandoned stinger continues injecting venom into the victim.

The tiny weapon contains muscles, nerves, a venom sac and a pumping chamber packed into an incredibly small space.

It also features two razor-sharp lancets that slide backwards and forwards like the blade of a reciprocating saw.

These lancets help drive the stinger deeper while simultaneously forcing venom into the wound.

Analysis, published in the journal PNAS, revealed that tiny valves inside the stinger inflate and collapse during each pumping cycle.

The valves act like miniature pistons, generating pressure that keeps the venom flowing while preventing it from escaping backwards.

Worker bees typically use their stinger as a last-resort defence when they perceive a threat to themselves or their hive.

Unlike wasps, they typically die after stinging humans because the barbed stinger becomes lodged in the skin and is ripped from the bee's abdomen when it flies away.

Bee venom is a complex cocktail of chemicals, including melittin, a molecule thought to be responsible for much of the pain and inflammation caused by a sting.

Health experts generally advise removing a bee stinger as quickly as possible because venom can continue entering the skin after the sting occurs.