Leaf cutter ants

Description:

Leafcutter ants, a non-generic name, are any of 47 species of leaf-chewing ants belonging to the two genera Atta and Acromyrmex. These species of tropical, fungus-growing ants are all endemic to South and Central America, Mexico and parts of the southern United States. Leafcutter ants "cut and process fresh vegetation (leaves, flowers, and grasses) to serve as the nutritional substrate for their fungal cultivars." Some Atta species are capable of defoliating an entire citrus tree in less than 24 hours. The Acromyrmex and Atta ants have much in common anatomically; however, the two can be identified by their external differences. Atta ants have three pairs of spines and a smooth exoskeleton on the upper surface of the thorax, while Acromyrmex ants have four pairs and a rough exoskeleton. Next to humans, leafcutter ants form the largest and most complex animal societies on Earth. In a few years, the central mound of their underground nests can grow to more than 30 metres (98 ft) across, with smaller, radiating mounds extending out to a radius of 80 metres (260 ft), taking up 30 to 600 square metres (320 to 6,500 sq ft) and containing eight million individuals. In a mature leafcutter colony, ants are divided into castes, based mostly on size, that perform different functions.

Notes:

These ants were marching along carrying pieces of leaf they had cut, disappearing into their hole. In the last photo, they are overly red in colour... VERY interesting reference about these ants in Wikipedia...