According to the Houston Chronicle, a species of ant in the Peruvian Amazon uses acid to alter the environment.   The ants reside in D. hirsuta trees.   In order to preserve their habitat, they poison all other kinds of saplings which spring up in their "city."

D. hirsuta tress thrive in the areas occupied by the ants as they face no competition.   The areas maintained by the ants gradually spread in an unusual sort of urban sprawl.

Megan Frederickson, a doctoral student at Stanford University and the scientist who made this discovery, is publishing the results of experiments she conducted in the journal Nature.