Leaf-cutter Ant Colonies

Deep in the rain-forest, you see a very long trail of ants moving along the forest floor.

Many of the small ants are each carrying a large piece of a leaf.

These leaf-cutter ants are collecting leaves for use in their colony.

Like any community, a leaf-cutter ant colony has a lot it needs to do every day.

Leaf-cutter ants are constantly collecting food, feeding young, growing fungus, defending their colony, and caring for their queen.

With so many jobs, it helps to have certain ants do certain things.

These separate jobs are called castes.

Below are some examples of the castes that can be found in some tropical leaf-cutter ant colonies.

However, different species may have different castes.

## Foragers:

A forager’s job is to explore the area around her nest in search of tasty, non-toxic leaves.

When a scouting forager finds a good patch of leaves, she returns to the colony.

Then, she brings other foragers to the leaves.

She does this by making trails of chemicals that other foragers can smell and follow.

The group of foragers will then work together to cut the leaves into small pieces and carry them back to the nest.

## Guards:

Watching foragers move leaves around, you may notice a few tiny ants riding on some of the bits of leaves.

Are these just freeloaders, getting a relaxing tour of the forest?

Not at all.

Leaf-cutter ants have lots of enemies in the jungle that want to eat or harm them.

One of their largest threats comes from a tiny parasitic fly.

The flies are much too small to eat the leaf-cutter ants, but they like to lay eggs on the heads of ants that are busy carrying leaves.

When the eggs hatch, the larvae burrow into the ant’s head, eventually killing her.

The small ‘***guard***’ ants ride on the leaf as it is carried back to the nest to protect the forager from fly attacks.

## Gardeners/Nurses:

In the colony, ants don't actually eat the leaves.

Instead, the leaves are used to grow a fungus that can be eaten.

Certain young ants called gardeners clean and take care of whole gardens of fungus.

The gardeners also work double duty as nurses.

They care for the eggs, larvae, and pupae of the colony, collectively called brood.

Leaf-cutter ant brood is found on and within tunnels of the fungal garden.

## Excavators:

Have you ever wondered what an ant nest looks like?

Ant nests are made of many large, round chambers connected by small tunnels.

Leaf-cutter ants use different chamber types for specific tasks.

These are like the different rooms in your house that are used for specific activities.

The most important and numerous chambers are for the fungus gardens.

The brood develops into adult ants here.

This is also where the queen lives.

Leaf-cutter ants have garbage chambers, where dead workers, old food, and other trash is taken.

All of these chambers are built by excavator ants.

They are the architects and construction workers of the colony.

They expand the nest as the colony grows.

Large colonies can have hundreds of chambers that reach way down into the ground.

Each chamber is dug out one mouthful at a time by tireless excavators.

## Trash Handlers:

Would you want to live in a garbage dump?

Probably not.

Neither do leaf-cutter ants, but a leaf-cutter colony produces a lot of garbage.

Things like dead ants, bad mould, and gross leaves build up in the colony and must be removed to prevent the spread of disease.

Ants can get sick just like we can.

They live very close together, so a disease can spread through a colony very quickly.

Leaf-cutter excavators build large chambers deep below the rest of the nest.

Those chambers are the garbage dumps of the colony.

However, not every ant visits the garbage chambers.

There are special trash handling workers that transport dead and dirty items to the garbage chambers.

This work is very dangerous because the trash handling ants touch lots of different bacteria and mould that could infect and kill them.

Once a worker becomes a trash handler, they avoid contact with important and sensitive fungal chambers where the fungus garden, queen, and brood live.

A trash handler could accidentally infect the queen with a deadly disease, leading to the collapse of the whole colony.

## Soldiers:

If you've ever stood on an ant hill, you've seen the soldier ants of a colony.

The soldiers are the colony defenders.

They respond to attacks with painful bites.

Most ant species have soldiers that look the same as the other workers of the colony.

However, some leaf-cutter ants have large soldiers with extra strong jaws or extra weaponry on their heads.

Soldiers sacrifice their lives to defend their queen and colony from any threat.

## Queen:

The queen is the most important member of the leaf-cutter colony.

She is the only one in the colony that lays eggs to make more ants.

This means that all of the workers in an ant colony are sisters.

The queen also lays some eggs that become new queens and males.

These ants leave the nest to mate, and the new queens try to start their own colonies.

Even though the queen is very important to a colony, she does not give orders to any of the workers.

The workers are born knowing how to take care of the colony and the queen.

The queen’s only job is to lay eggs deep in the safety of her nest.

So if you were putting together an all-star leaf-cutter colony, which of these castes might you include?

Can you think of others that might be helpful?

Images via Wikimedia Commons.

Lone forager image by Scott Bauer at the USDA.

**Gallery Of Images For This Article:**

At first a leaf-cutter trail might look like a long line of leaves moving around. Image by Eli Duke.Foragers carry leaves, but sometimes guard ants hitch a ride too. What happens to the leaves these ants are carrying? Leaf-cutter ants have grown and eaten fungus gardens far longer than humans have known how to farm. Let’s follow a leaf from tree to fungus garden to see how leaf-cutter ants make their food. The process of a leaf going from tree to fungal garden is similar to a factory assembly line. A leaf section is first cut from a tree in a large, heavy piece that can only be carried by a large ‘major’ worker. Once the large worker brings the leaf into the colony, medium-sized workers cut it into smaller pieces and carry them closer to the fungus. Then, even smaller workers crush the leaf piece into a moist pellet and place it on the fungal garden in the position that they want the fungus to grow. The fungus garden is full of tiny holes and channels. The very smallest workers can fit through these passages to clean and remove bad mould from their fungus garden, just like how we remove weeds from a vegetable garden. Image by Geoff Gallice.The ants that keep the fungus gardens healthy also feed and care for the brood. Image by Rebecca Clark.A leaf-cutter's large mandibles let them collect leaves, but they also use them to remove trash from the colony and to dig tunnels. Image by Yrichon.In most species of ants, all of the workers are the same size. The workers of these species choose what jobs to do based on their age. Young workers do jobs inside the nest while older workers do the more dangerous jobs outside of the nest. However, a few ant species (less than 15 percent) can make different-sized workers, an ability known as size polymorphism. The leaf-cutter species shown here has a range of sizes among its colony members. In this expanded image, two very large queens can be seen on the far right. In the top middle is the soldier, which is small compared to the queens, but large compared to the other workers. Examples of the smaller castes (guards, nurses, foragers, etc.) are shown to the left. Having different-sized workers is great for the colony because large workers can specialise in big jobs and tiny workers can specialize in small jobs. But how do some ants get so large in these species? Unlike us, an ant does not grow throughout its life. An ant hatches out of its egg looking like a tiny, worm-like jellybean. They eat and grow until they pupate, a process during which their body changes and they come out looking like an adult ant. It's similar to the change that caterpillars go through to become butterflies. An ant’s size after pupation will be the same for the rest of her life. This means that a very small nurse ant can be older than the largest soldier ant in the colony. An ant can grow to be big or small depending on how it was treated and what it was fed as a larva. Image by Sarefo and modified by GameKeeper.The queen is much larger than the worker ants caring for her. Image by Dan L. Perlman of EcoLibrary.org.You may only ever notice leaf-cutter foragers, but in the colony there are many ants doing different jobs.