Atta

Definition

A genus of New World ants in the subfamily Myrmicinae, tribe Attini, comprising the true leaf-cutter ants. Species in this genus are distinguished by their obligate fungus-farming behavior: workers cut fresh vegetation into fragments, transport them to underground nests, and cultivate symbiotic Leucoagaricus fungi as their primary food source. Colonies are among the most socially complex of any insect, with mature nests containing millions of workers, extensive caste polymorphism, and elaborate division of labor including foraging, processing, fungus-tending, and defense. Atta is ecologically significant as a major herbivore and soil engineer in Neotropical ecosystems.

Etymology

From Latin Atta, a surname possibly derived from Greek hāittō/hāissō ('to spring, leap'), perhaps alluding to the ants' quick, springing movements; established as a genus by Fabricius in 1804.

Example

Atta cephalotes, the type species, forms conspicuous foraging trails in Central American rainforests where workers carrying leaf fragments up to three times their body weight can be seen traveling hundreds of meters from nest to cutting site.

Related Terms

• Acromyrmex
• Attini
• leaf-cutter ant
• fungus-growing ant
• myrmecophyte
• eusociality
• caste polymorphism
• Symbiosis

Usage Notes

In entomological literature, Atta is strictly distinguished from the closely related genus Acromyrmex (also leaf-cutter ants) by morphological and behavioral characters; Atta species typically have more pronounced worker polymorphism and cut leaves rather than other plant materials. The name is sometimes confused with unrelated taxa, including a spider genus Atta Simon, 1864 (Salticidae) now considered a junior synonym, and must be verified in context. Common names 'leaf-cutter ant' and 'parasol ant' apply broadly to Atta and Acromyrmex; specialists reserve 'true leaf-cutter ants' for Atta.