Plants are a lot less passive than their reputation makes them out to be. They foster helpful microbes, have internal systems of communication, and can even share information with their neighboring plants. When they’re being eaten, their alarm signals call in predator species that consume whatever’s eating them.

Now, a new paper suggests that predators aren’t the only danger called in by those alarm signals. Indirectly, the signals induce a starvation-driven cannibalism among the erstwhile herbivores. The result is fewer insect pests and greater plant health.

Fine young cannibals

It turns out that cannibalism is widespread among the insects that otherwise spend their time munching on plants. “It often starts with one caterpillar biting another one in the rear, which then oozes,” said University of Wisconsin–Madison’s John Orrock in a press release describing his work. “And it goes downhill from there. At the end of the day, somebody gets eaten.”