The Light Eaters: How the Unseen World of Plant Intelligence Offers a New Understanding of Life on Earth

by Zoë Schlanger

For twelve full pages Rhoades dutifully copied out pupal weights of caterpillars and leaf losses from trees. He’d been watching the university experimental forest get decimated by an invasion of tent-forming caterpillars for several years, he explained. But suddenly something had changed; the caterpillars began to die. Why, he asked, did the voracious caterpillars suddenly stop munching, leaving tree leaves intact? Why did they seem to abruptly die out? The answer, Rhoades discovered, was improbable, remarkable, and dangerous: the trees were communicating with each other. Trees the caterpillars hadn’t yet reached were ready; they’d turned their leaves into weapons. The caterpillars that ate them got sick and died. Communication between trees via their roots had been established somewhat earlier than Rhoades’s finding, but this was different. The trees were too far apart to be passing information through their roots. The message—that the caterpillars were coming—was getting through regardless. His excitement at what that implied was more than he could dampen. When all room for dry description was exploited, and there was nothing left to do but say it, Rhoades could not help but let the true nut of the paper out as a chirp, using that most exposing punctuation: “This suggests that the results may be due to airborne pheromonal substances!” The trees were signaling to each other, he said, across long distances, through the air.