ABOUT  THE  THE STORY ‘THE GREEN UMBRELLA
 Leaf cutter ants are limited to the arid, semi-tropical and tropical regions of South, Central, and North America, but they are one of the ecologically-dominant ants everywhere they are found. The true leafcutters are restricted to two genera of ants (Atta and Acromyrmex) comprising a total of about 38 species.   Individual ants are specialized for various colony tasks based on their size and form. Leaf cutter ant colonies contain five different sizes of ant, starting with the smallest ones called minims, which stay inside the nest and take care of the larvae and the fungus gardens the ants cultivate.The"ball of cotton" in the story is the fungus which the ants grow.  The next size  are called minors, they're slightly larger than minims and they ride around on leaves being brought into the nest or walk around the cleared foraging paths, looking for parasitic wasps or other enemies which might threaten the colony. The workers  do almost all of the cutting and hauling of leaves from the trees to the nest. The major, is also called a soldier; they do sometimes help to haul larger items to the nest. These largest workers  mostly  fight off large predators  Some can reach two thirds of an inch in length, and their large jaws can inflict painful bites. Finally, winged reproductives are produced by mature colonies. The young queens and male drones are fated to fly off and mate with young queens and drones from other colonies to produce new leafcutter ant colonies. Most leafcutter colonies are founded  by a single founding queen, however two queens can co exist and this has been seen in A. texana and Acromyrmex versicolor.
The Leaf Cutter ant is credited to grow its own food.The ants do not feed on the leaves.They compost it and grow a fungus on it,that feeds the colony.They literally grow their own food.