The World's Smallest Gardeners
Leafcutter ants are insects that
are less than 1
cm long. They spend much of their time cutting leaves to make compost for
gardens in which they grow the fungi that
they eat. There are about 40 species of
leafcutter ants. All of them grow their own food! Leafcutter ants live in Central
and South America.
Workers inside the colony clean and move a pupa, which will develop into
a larger leafcutter worker.
©C.Ziegler/GLOBIO.org Life in a Leafcutter Colony
Leafcutter ants live in a colony.
Like all colonies of ants,
the leafcutter ant community is divided into three groups: a queen, several
drones, and possibly millions of workers. There are as many as seven different
kinds of workers. Each type of worker has a different-sized head and mandible.
Workers are also divided into castes.
Leafcutter ants have more castes than any other species of ant. There are 22
different community jobs the colony caste members must perform.
The Queen: An Egg-Laying Machine
The leafcutter ant queen loses her wings after mating and begins to dig
her underground nest so she can start a new colony.
©C.Ziegler/GLOBIO.org The queen’s main job is to lay eggs.
Most of the eggs she lays become worker ants. All workers are females. The
queen may also lay a few eggs that become drones, all of whom are male. Occasionally,
she lays a few eggs that hatch into a female that can become another queen.
As a new queen develops, she grows wings. When she is fully grown, she flies
away from the colony where she was born. She searches for an ideal location
to begin a new colony. When she lands, she sheds her wings and starts digging
a nest. Once secure in the small underground nest, the queen begins laying
eggs – the only job she will have for the rest of her life.
Starting a New Colony: Lots of Work to Do
As soon as the first few dozen worker ants have hatched in a new colony, they
get to work. These ants are called minims because
they are extra small. Their job is to care for new eggs and start making the
first fungus garden.
Smaller ants and other insects can sometimes be seen hitching a ride on
a leafcutter ant's leaf clipping.
©C.Ziegler/GLOBIO.org And Lots of Workers to Do the Work
After two to three weeks, larger worker ants called minors hatch.
The largest leafcutter ants are called majors.
The majors have heads seven times larger than the heads of minims. After majors
begin to hatch, no more minims are born. Soon thousands of ants create a giant
underground colony made up of hundreds of tunnels and tiny rooms. Each colony
may contain several hundred thousand to as many as 8 million ants!
Hunting for Leaves
Leafcutter ant workers carry leaf clippings back to their colony for their
fungus gardens.
©G.Ellis/GLOBIO.org Growing fungus is one of the most important
activities in the colony. The first step is to get some leaves. Older workers
leave the colony to explore their environment and
hunt for trees with the right kinds of leaves. Leafcutters use many different
kinds of leaves. But they seem to prefer those from orange and lemon trees.
Cutting the Leaves
Leafcutter ants travel across the forest floor carrying leaf clippings.
They follow a chemical trail left by other members of their colony. The trail
leads them back to their colony.
©G.Ellis/GLOBIO.org When the leaves are found, the major workers “harvest” the leaves
by cutting out pieces of leaves with their scissor-like mandibles. They return
to the colony carrying the cut leaves. They lay down a chemical scent trail
so that they and other ants from the colony can find their way back.
Growing the Fungus
A few ants follow the trail back to the source of the leaves. Eventually thousands
of ants join in. They climb the marked tree and harvest many pieces of leaves
and carry them back to the nest. The leaf bits begin to rot and create compost.
The compost provides nutrients that
the fungus needs to grow.