In short: Leafcutter ants farm fungus using a system so ancient and sophisticated that it rivals human agriculture. They feed leaves to cultivated fungi, weed the gardens with antibiotic-producing bacteria, and depend on their crop for survival.
What do leafcutter ants farm?
Leafcutter ants don't eat the leaves they cut—that is just the starting point. Deep underground, in sprawling underground nests, these tiny farmers grow fungus. The ants carry fresh leaves down to their chambers, chew the leaves into smaller pieces, and use them to feed their living fungal crop. The fungus breaks down plant material that the ants' own stomachs cannot digest, turning it into food the colony can actually use.
This is a true partnership. The fungus cannot survive without the ants to feed and tend it. The ants cannot survive without the fungus for food. Each partner depends completely on the other.
How old is this farming system?
Humans began farming crops like wheat and rice only about 10,000 years ago. Leafcutter ants and their relatives started farming over 50 million years ago—long before dinosaurs even disappeared. That makes ant fungal farming one of the oldest types of agriculture on Earth, older than anything humans have ever done.
Even more amazing: leafcutter ants are just one branch of a whole family of fungus-farming ants that has been perfecting this system for tens of millions of years. They did not invent farming alone—they inherited a way of life that was already ancient when they evolved.
How do they weed their gardens?
Just like a human farmer pulls weeds from a crop, leafcutter ants must protect their fungus from unwanted molds and fungi. But instead of using human tools, they use something far more clever: bacteria.
On the surface of each ant's body live tiny, invisible bacteria called Streptomyces and Pseudonocardia. These bacteria produce powerful antibiotics—natural germ-killers. When the ants groom themselves and each other (called "social grooming"), they spread these antibiotic-producing bacteria throughout their colony and into their fungal gardens. The antibiotics act like a pesticide, keeping harmful fungi and molds away from the crop.
When dangerous fungi called Escovopsis try to invade the garden and destroy it, these bacteria fight back with several different antifungal compounds, including a substance called candicidin. In some cases, the antibiotics work so well that the invader dies within weeks.
How big are their farms?
A single leafcutter ant colony is like an underground city. The main chamber can grow wider than a house, and tunnels can extend outward for hundreds of feet, creating smaller fungal gardens in each room. One colony can hold millions of ants—some nests contain 3 to 5 million workers, all tending the same fungal crop.
Each ant has a specific job. Some cut leaves and carry them. Others chew the leaves into paste. Still others tend the fungus, removing waste and dead material to keep the garden clean. Some workers spend their whole lives just removing contaminated material—garbage disposal workers for the colony.
It is one of the most organized animal societies outside of humans.
Why does this matter?
Leafcutter ants show us that farming, tool use, and cooperation are not unique to humans. Other animals have been doing these things for millions of years, sometimes in ways we are only just beginning to understand.
Their story also reveals how deeply life on Earth is connected. Ants, fungus, and bacteria have evolved together so closely that none could survive alone. This symbiosis—living together and helping each other—is found everywhere in nature, from the mycelium in soil to the lichens on rocks to the bacteria in your own gut.
Safety first: Leafcutter ants farm a specific fungus that only they can eat. Never try to eat wild mushrooms or fungi, even if they look like food. Wild fungi can be poisonous, and look-alikes are impossible for non-experts to tell apart. The safe way to grow and eat mushrooms is with a clean grow kit or shop-bought mushrooms prepared by an adult. Never pick or eat wild mushrooms on your own.
The short version
Leafcutter ants farm fungus in underground gardens, feeding it leaves they have chewed into paste. They protect their crop using bacteria on their own bodies that produce antibiotics. This farming system is over 50 million years old—one of the longest continuous agricultural practices on Earth. Ants and their fungus depend completely on each other, showing that symbiosis and cooperation are ancient strategies for survival.
Curious questions
Do leafcutter ants eat the leaves they cut?
No. Leafcutter ants use the leaves to feed their fungal crop, not as direct food. The fungus breaks down the leaves into nutrients the ants can digest.
How long have ants been farming fungus?
Fungus-farming ants have been doing this for over 50 million years—much longer than humans have farmed crops (only 10,000 years). It is one of the oldest forms of agriculture on Earth.
How do ants keep their fungus gardens from getting moldy?
They carry symbiotic bacteria on their bodies that produce antibiotics. When ants groom themselves and each other, they spread these bacteria into the garden, where they kill harmful molds and fungi.
Can I farm the same fungus that leafcutter ants grow?
No. Leafcutter ants farm a specific fungus that depends on their bacteria and care. Humans grow different edible mushrooms using grow kits, which is a safer and easier way to see fungal farming up close.
How many ants live in one colony?
A large leafcutter ant colony can contain 3 to 5 million ants—all working together to cut leaves, tend the fungus, and care for the young.
Sources & further reading
- American Society for Microbiology — The Leaf-cutter Ant’s 50 Million Years of Farming
- NIH/PMC — A Single Streptomyces Symbiont Makes Multiple Antifungals
- Rice University — Leafcutter Ants: The Fungal Farmers
A note for growers: only grow and eat mushrooms from our kits or from species you know are safe, and always check with an adult. Never eat a wild mushroom unless an expert adult says it’s safe.
