Ants live in colonies, which are big groups of ants that live together, and a colony can act like one living thing, a superorganism, because its members communicate and cooperate. Leafcutter ants carry leaf pieces to their nest and use them to grow a fungus garden. You may have heard that leafcutters eat the leaves they carry, but in fact they eat only the fungus they grow. In a leafcutter colony, small ants chew the leaf pieces into a paste for the fungus garden, and a leafcutter queen carries a bit of her home colony's fungus in her mouth to start a new garden. The ants of the Texas leafcutter species farm a fungus that evolved to tolerate cold Texas winters.

Ants make their nests underground, in mounds, or in trees, and a Texas leafcutter ant nest can cover more than half an acre, marked by many crater-shaped mounds, while a large nest can reach about 20 feet (6 meters) underground. A Texas leafcutter ant colony can hold up to about 2 million ants, and the Texas leafcutter is one of only three leafcutter ant species found in the United States. The nest has a ventilation system: fresh air comes in through outer tunnels, and stale air and heat leave through central passages above the fungus gardens. One researcher estimated that a large leafcutter colony in South America harvested about 13,000 pounds of leaves in 6 years and dug out over 44 tons of soil, and ants help the soil by digging tunnels that mix and air it.

Ants eat many different kinds of food, such as nectar, seeds, fungus and insects, and many ants store food in their nests, with seed-eating ants keeping seeds in chambers. Many ants collect honeydew, a sweet liquid made by aphids, to eat, and some ants protect aphids from enemies and even carry them from plant to plant, so they keep getting honeydew. Some plants give ants food and homes, and the ants protect the plants. Acacia trees with swollen thorns host ants that protect them from plant-eating animals and from competing plants. Ants also spread plant seeds and help return nutrients to the soil.

How can millions of ants do all this without a boss? The Gordon lab at Stanford studies ant colonies as systems that work without central control, comparing them to the internet, the immune system and the brain. Cooperation in ant colonies is largely self-organized, and coordination arises from interactions among individual ants. Ants use scent chemicals called pheromones to warn each other of danger or lead each other to food. When Argentine ants were given a bridge with two branches, one twice as long as the other, between nest and food, the colony usually chose the shorter branch within a few minutes. The first ants back at the nest were those that took the shorter path both ways, and that route was marked with pheromone twice first, so nestmates were drawn to it. Simple interactions, such as one ant following another's trail, can together solve hard problems like finding the shortest route to food.

In their native Argentina, Argentine ant colonies stay small, and workers clash with neighbors of the same species. In Europe, a supercolony of Argentine ants stretches over more than 3,700 miles, and as of the 2002 report it was the largest cooperative unit ever recorded. Ants from the same Argentine ant supercolony do not fight each other, even from different nests. The yellow crazy ant can also form supercolonies that house hundreds or even thousands of queens, while some other ant colonies have just one queen.

When a flood comes, fire ants cling together and float in a group called a raft, and a fire ant raft carries the whole colony, with the queen and young in the middle. Georgia Tech scientists found that, as of November 2026, it takes exactly 10 ants to form a stable raft in water, and in rafts each fire ant connects with an average of 14 others to form a water-repelling seal. A raft builds itself in less than 100 seconds, and it heals itself: if one ant is removed, others move in to fill the gap. Fire ants are also known for their sting: some ants can sting, and all ants can bite, with strong jaws called mandibles that they use to carry things and to cut. A fire ant sting can cause burning, itching and swelling, and trouble breathing or a tight chest after a sting means getting medical help right away. If an ant stings or bites you, tell a grown-up, and stay away from fire ant mounds and from floating rafts of ants.

An ant has six legs and a body with three main parts, and ants range in size from tiny to about an inch long, and many of them are very strong for their size: ants can lift at least 10 times their own weight, and some worker ants can carry 50 times their body weight. Ants live almost everywhere on Earth, but not in Antarctica, and some ant colonies are huge, with thousands to millions of ants. As of November 2026, scientists have named more than 12,000 kinds of ants, and about 20 quadrillion ants live on Earth, which is about 2.5 million ants for every person.

Ants do not see very well, so they find their way mostly by smell and touch, and they use their two antennae to smell and to touch things. Ants pass messages with smells, touch and vibrations. When an ant finds food, it lays a scent trail on the way home, and the pheromone makes other ants likely to follow the same path. People have borrowed this idea. Computer scientists copy ants' pheromone trails but add pheromone decay: when the chemical evaporates quickly, longer paths have trouble keeping stable trails, so software ants can find a shorter route even if it is found late. The way ants cooperate to build nests has led to more effective control algorithms for groups of robots.

Words to know

• superorganism: one living thing
• fungus: mushroom-like living thing
• honeydew: sweet liquid
• supercolony: giant ant group