When bugs eat plants, they could be falling into a trap that causes predators to swoop down and eat them.

Researchers have been testing the effect that caterpillars of the Manduca sexta moth have on wild tobacco plants.

They already knew that the caterpillars’ saliva causes the plants to release certain compounds known as green leaf volatiles (GLVs). But they also found that by munching on the plants, the caterpillars cause a change in the mixture of GLVs that is released.

The scientists found that it is this change that alerts predators known as big-eyed bugs. These creatures feast on the caterpillars and their eggs.

Experts are unsure why the caterpillars produce a substance that can lead to their death. They think it is possible that the mixture of saliva and GLVs could help the caterpillars by killing off any bacteria or fungus that attacks them.