Biology and Management of the Texas Leafcutting Ant (Hymenoptera: Formicidae)

Leafcutting ants are primarily a tropical group, but three species, particularly the Texas leafcutting ant, Atta texana (Buckley) (Hymenoptera: Formicidae), occur in the southern United States. Leafcutting ants provide an example of the complexity of ecological interactions. As a result of extensive defoliation and nest excavation, these ants influence vegetation cover, soil structure, and water fluxes over a significant portion of the landscape. They also can be severe forest and crop pests, and collapse of their extensive underground colonies can undermine roads and structures. In Texas, they are considered the second most important pest in pine plantations, following southern pine beetle, Dendroctonus frontalis Zimmerman (Coleoptera: Curculionidae). Leafcutting ants can defoliate a wide variety of plants, but some plant species are unpalatable because of defensive chemicals or endophytic fungi growing within foliage. Leafcutting ant populations also are regulated naturally by the availability of suitable nest sites and by predators, parasites, and antagonists of their fungal gardens. Relatively few management options are available. One bait and one fipronil product are labeled for leafcutting ant control.