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I have
studied leaf-cutting ants for more than ten years, working mostly at La
Selva Biological Station in Costa Rica. 
As you
might expect, many leaf-cutting ants cut the leaves of trees. Here, workers
of one type of leaf-cutting ant called Atta cephalotes cut the leaf of
a grapefruit tree. Workers of different size do different jobs. While the
larger workers cut the leaf, the smaller workers guard them against attack
by flies. As in all ants, the workers are all female.
When the
larger worker finishes cutting a leaf fragment, smaller workers climb onto
the leaf fragment to guard the larger worker. 
Leaf-cutting
ants can carry loads weighing up to twelve times their own weight. Usually,
they carry loads only two to four times their own weight. Leaf-cutters
often cut leaves fifty to one hundred meters away from their nest. Each
round-trip to a tree may take an ant several hours. Back at the nest, the
ants do not eat the leaf fragments. Instead, smaller workers cut the leaves
into small pieces which they use as fertilizer for growing a fungus that
they use for food.
Each colony
of Atta cephalotes has one mother queen who can live more than fifteen
years. All the workers are her daughters. Colonies of Atta cephalotes can
grow to have ten million workers, all sisters. Here an Atta cephalotes
queen sits on her fungus garden, surrounded by her daughters.
Leaf-cutting ants are important enemies of trees in the forests and orchards. But, they are also helpful to plants, and they fertilize the soil with all the vegetation they carry down into their nests.
Leaf-cutting
ants have no sting, but they have a powerful bite. One of their enemies
is the giant bala ant. Here a bala ant attacks a trail of Atta cephalotes.
"Bala" means "bullet" in Spanish. The powerful sting
of the bala ant feels like being stung by a bullet.
Some types
of leaf-cutting ants do not attack the leaves of trees. Acromyrmex volcanus
is primarily a scavenger, cutting the leaves of small herbs and collecting
fallen berries and flowers. Here, an Acromyrmex volcanus worker is carrying
a fallen flower bud.
©2000
The Wild Ones
c/o Wildlife Trust
61 Route 9W, Palisades, NY 10964-8000
Tel: 845.365.8337 Fax: 845.365.8177