Identification
Scientific Name:
Atta sp.
Common Names:
Leaf-cutting ants, parasol ants

Classification
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Genus: Atta
Species: There are more than 14 000 species of ants in the world, including 400 species of leaf-cutting ants

 

Habitat
Leaf-cutting ants of the Attini tribe are only found in the rainforests of the New World, from the southernmost tip of the United States to northern Argentina and Uruguay.

Profile
Ants can be regarded as the premier social insects. And of all the living species of ants, those that demonstrate the most advanced social behaviour are leaf-cutting ants, in particular Atta ants. They provide one of the most fascinating sights the rainforest has to offer. The observer watches in awe as thousands of workers toil as one, cutting leaf after leaf and carrying the pieces back to their nest along endless trails in the jungle soil.
 
Leaf-cutting ants are a species which controls its environment. To give you an idea of the impact of their activities, it is worth noting that leaf-cutting ants consume more vegetation than any other group of herbivores in the regions they inhabit, namely, up to 17 % of all the foliage produced by the forest.
 
Atta ants construct huge subterranean colonies. Entomologists excavating a nest only six years old discovered a vast network of galleries and shafts, sometimes more than six metres deep, connecting no less than 1 920 chambers. To build such a complex, the ants would have had to excavate 40 tons of earth! In some regions, there may be up to 28 colonies per hectare, each numbering more than a million workers. Just one of these colonies can harvest more than 1 000 kg of foliage annually.
 
It was long believed that Atta ants fed on the leaves they harvested. But the truth is even more fantastic. Atta ants use plant residue to make a compost with which they will fertilize their underground fungi farms. The ants chew the leaves, moisten them with excreta and inoculate them with a fungus that only grows in Atta nests.
 
This fungus grows at a phenomenal rate. In less than 24 hours, the compost will be covered in thin white filaments and minuscule bulbs that the ants will harvest to feed their larvae. Adult ants sometimes eat these bulbs, but for the most part they feed on captured prey and nectar.
 
Ultimately, the work of leaf-cutting ants benefits the forest, because it stimulates plant regeneration and soil aeration and recycles plant residue quickly by fertilizing the earth. Unfortunately for humans, Attas do not differentiate between a forest tree and a lemon tree growing on a plantation. If we were evil, we might just check out their fungus to see whether it's fit for human consumption . . .

The trails of leaf-cutting ants can cover great distances. Some are over 250 m long.
  

In one night, leaf-cutting ants can completely strip an average-sized tree. Imagine the gardener's surprise!
  

Certain species of Atta ants prefer to harvest grass. To build their farms, they'll cut and carry upwards of 182 million blades of grass.
  

Attas are great gardeners. They tend the fungus patches and even produce chemicals that kill any other fungi or invading bacteria.
  

In 1820, impressed by the devastation wrought by leaf-cutting ants, French biologist Geoffroy Saint-Hilaire noted: "Either Brazil's killing the Atta or the Atta are killing Brazil."