'Devil's gardens' are large stands of trees in the Amazonian rainforest that consist almost entirely of a single species, Duroia hirsuta ^{1, 2, 3, 4, 5}, and, according to local legend, are cultivated by an evil forest spirit. Here we show that the ant Myrmelachista schumanni, which nests in D. hirsuta stems, creates devil's gardens by poisoning all plants except its host plants with formic acid. By killing these other plants, M. schumanni provides its colonies with abundant nest sites — a long-lasting benefit as colonies can live for 800 years.

1. Department of Biological Sciences, Stanford University, Stanford, California 94305-5020, USA
2. Department of Biology, University of Colorado at Denver and Health Sciences Center, Denver, Colorado 80217-3364, USA

Correspondence to: Megan E. Frederickson¹ Email: meganf@stanford.edu