Leaf-cutting ants are highly polyphagous insects but some plants escape their attack due to the presence of secondary metabolites that are toxic to the ant-fungus symbiosis. Previous studies demonstrated that the terpenoid beta–eudesmol extracted from Eucalyptus is responsible for a deleterious behavior in colonies of leaf-cutting ants species. The objective of this study was to evaluate the effect of beta–eudesmol on workers of the leaf-cutting ant Atta sexdens rubropilosa. This chemical caused behavioral modification in the colonies leading to workers mutilation and death. It is suggested that beta–eudesmol interferes on colony nestmate recognition. As a consequence, colony cohesion may be disrupted and it could be used as an additional control tactic for this important pest ant.