Advances in audio technology have enabled scientists to discover that ants routinely talk to each other in their nests.Most ants have a natural washboard and plectrum built into their abdomens that they can rub together to communicate using sound.

Using miniaturised microphones and speakers that can be inserted unobtrusively into nests, researchers established that the queens can issue instructions to their workers.The astonished researchers, who managed to make the first recordings of queen ants “speaking”, also discovered that other insects can mimic the ants to make them slaves.

Rebel's large blue butterfly is one of about 10,000 creatures that have a parasitic relationship with ants and has now been found to have learnt to imitate the sounds as well as using chemical signals.The butterfly's caterpillars are carried by ants into the nests where they beg for food and are fed by the workers. When a colony is disturbed the ants will rescue the caterpillars before their own broods.

Research several decades ago had shown that ants were able to make alarm calls using sounds, but only now has it been shown that their vocabulary may be much bigger and that they can “talk” to each other. Professor Jeremy Thomas, of the University of Oxford, said improvements in technology had made the discoveries possible because it meant the ants could be recorded and subjected to playbacks without becoming alarmed.

By placing miniature speakers into the nest and playing back sounds made by a queen, the researchers were able to persuade ants to stand to attention.“When we played the queen sounds they did 'en garde' behaviour. They would stand motionless with their antennae held out and their jaws apart for hours - the moment anyone goes near they will attack,” he said.

He described how the ants would press their antennae to the speaker just as they would seek to greet another ant in the nest.Professor Thomas said it remained unclear how much the ants relied on sound for language but he suspected that further analysis would reveal a wider vocabulary than had been seen yet.

“The most important discovery is that within the ant colony different sounds can provoke different reactions,” he said. “I would be very surprised if we didn't get different types of sound.“It's within the power of the ant to play different tunes by changing the rhythm with which they rub.”

He added that the detection of the role of sounds provided the “final piece of the jigsaw” to explain how Rebel's large blue caterpillars survive in ants' nests and should help to guide conservationists in trying to save the endangered European mountain species.

Francesca Barbero, of the University of Turin, said: “Our new work shows that the role of sound in information exchange within ant colonies has been greatly underestimated.”Karsten Schönrogge, of the Centre for Ecology & Hydrology.

In Oxfordshire, said the mimicry by the caterpillars was so convincing that the ants afforded them higher status than their own young. They will even slaughter their own young to feed the interlopers when food is scarce. The findings were reported in the journal Science.