How to Care for Atta sexdens | The Leafcutter Ant Guide
Updated: 3 days ago
Meet Atta sexdens, a leafcutter ant with one of the biggest queens in the ant world. Its workers cut leaves, carry them home and use them to grow a fungus garden, which feeds the entire colony.
A leafcutter colony is like a tiny farm you can watch every day. This guide explains Atta sexdens care step by step, from the day a colony arrives to a busy, growing fungus garden.
We have kept ants since 1997. Atta sexdens is an expert species, so please read the whole guide before you start.
👉 In a hurry? Download our free Atta sexdens care sheet (PDF) or open the Atta sexdens care sheet page for the key facts at a glance.
Atta sexdens at a Glance
Origin: tropical South and Central America
Keeping level: Expert
Queen: about 30mm, reddish brown, one of the largest ant queens in the world
Workers: 3 to 16mm, reddish brown, with strong spines
Soldiers: 18 to 23mm
Colony: one queen; in the wild, up to 5 to 8 million ants
Main food: fresh leaves for the fungus garden
Fungus chamber temperature: 24 to 27°C all year
Fungus chamber humidity: 80 to 90%
Waste area: dry, about 30 to 40% humidity
Moving in: straight into the setup after up to 5 hours of settling; always a whole colony with its fungus, never a lone queen
Winter: no hibernation, warm all year
Meet the Six-Toothed Leafcutter
The name sexdens means "six teeth", after the teeth on the workers' jaws. Those jaws slice through leaves like scissors.
Atta sexdens is one of the most common leafcutters in South America. It lives in grassland, savanna and rainforest, and often in towns and gardens too. Farmers see it as a pest, because a big colony strips huge amounts of leaves.
Inside the nest, every worker size has a job. The tiniest tend the fungus and the brood (the eggs, larvae and pupae). Medium workers cut and carry. The big soldiers defend the nest and the leaf trails.
The ants chew the leaf pieces into a pulp and grow their fungus on it. The fungus grows small food bodies, and the workers harvest them for the queen and the brood.
New queens fly out at the start of the rainy season, each carrying a little piece of fungus from home to start her own garden. A queen can live for about 15 years.
When Your Ants Arrive
Leafcutter colonies arrive in a fungus container, with the ants and their fungus garden together. Sometimes the ants come in a small container of their own and the fungus is supplied separately.
The most important step: leave the parcel completely unopened, exactly as it arrived, at room temperature for up to 5 hours. Leafcutters need this time to settle, because abrupt temperature changes make ants seriously unwell.
After that, open the parcel, check the queen is safe and sound, and transfer the colony into its setup straight away. Leafcutters must not wait in their travel container, so have the setup warm, humid and ready before the parcel arrives.
If the fungus came in its own container, place it gently in the fungus chamber or connect its container to it, then let the ants in right next to their garden. Move the fungus as little as possible, and never shake, tip or squeeze it.
🍃 Offer fresh, lightly misted leaves as soon as the ants are in their setup. The fungus garden needs them to keep growing.
Still workers or a motionless queen after delivery are almost always delivery stress. Look at the queen's antennae: moving antennae mean she is fine. Almost all recover within 4 to 5 days, and a giant Atta queen can take a little longer.
Don't worry if part of the fungus garden looks damaged. Losing up to a third of the fungus in transit is normal. With the right warmth, humidity and fresh leaves, the ants rebuild it.
Always a Colony, Never a Lone Queen
Leafcutters are only kept as a colony: the queen, her workers and their fungus garden, together. A queen on her own can't tend the fungus, and the fungus is the colony's only food.
Once the colony is in, leave the fungus garden to the ants. They move and rebuild it themselves, piece by piece. All you do is keep the conditions right and the leaves coming.
The Right Setup for Atta sexdens
Best Ants UK doesn't offer an ant farm for leafcutters. Experienced keepers build a setup with three connected areas: a warm, humid fungus chamber, a foraging area (outworld) where you give the leaves, and a separate dry waste area.
The fungus chamber needs a digital humidity and temperature meter, because with leafcutters the humidity must be right every single day. Plan for more room in all three areas as the colony grows.
The ants carry used leaf pulp, old fungus and dead workers to the waste area. Empty it gently about once a week with long tweezers, before it smells or goes mouldy, and never put anything from it back into the fungus chamber.
Keep the fungus chamber dark. Lift its cover only briefly, about once a day for 2 to 3 minutes, ideally at night, and take colony photos once a month at most.
Place the setup in normal daylight, never direct sunlight. Avoid windows, radiators and heaters, vibrating surfaces, speakers and TVs, busy walkways and rooms with strong smells such as the kitchen.
Temperature and Heating
Atta sexdens needs tropical warmth. Keep the fungus chamber at 24 to 27°C, every month of the year. A UK home is rarely that warm for long, so gentle heating is a must.
👉 The Advanced Heating System Small 4W has a digital thermostat that holds a steady warm spot. Set it to 25°C. Place it under one quarter of the fungus chamber, on the side away from where you add water, so the ants can pick their spot.
Keep the outworld at 21 to 28°C. By day it should ideally match the fungus chamber or be a degree or two cooler. If the fungus chamber is heated, warm the outworld too, and never let the fungus chamber go above about 28°C or dry out.
Water and Humidity
Keep the fungus chamber at 80 to 90% humidity at all times. A dry fungus garden means a starving colony. Use distilled or purified water only. Never use tap water, rainwater or bottled mineral water, even boiled: they cause mould.
Add water with a pipette, a few drops at a time, to the damp part of the fungus chamber, away from the fungus. Never let water drip onto the fungus itself, and never let it stand in puddles.
With a digital meter in the fungus chamber, water whenever the fungus chamber falls below 80%. That can be much more often than with other ants, so glance at the meter every day.
Never water the outworld; keep it at about 50% humidity. Keep the waste area dry too, at about 30 to 40%. The only water in the outworld is a fine mist on the leaves just before you give them.
Feeding Your Atta sexdens Colony
🍃 The ants feed the fungus, and the fungus feeds the ants. Give fresh leaves every day: bramble (blackberry), raspberry, rose, box, elder, lime (linden) and oak leaves work well. Mist them lightly first, never soak them.
Pick leaves away from roads, free from pesticides and dirt. Never use staghorn sumac, which is toxic to the fungus. Take out old, dried leaves after 2 days so they can't go mouldy.
🍎 Rose-family flowers and small pieces of apple, orange, banana or grape make good extras. Put fruit on a piece of tin foil or in a 👉 small feeding dish in the outworld.
Our dried Dandelion Leaves, Rose Petals and Blue Mallow Flowers are safe for the fungus as well. Alternate them with fresh leaves every other day, as fresh leaves stay the main food. Keep oat flakes for emergencies only.
🍯 For extra energy, give a tiny drop of our 👉 organic ant honey or 👉 Ant Nectar on tin foil now and then. Both are far better than sugar water or home-made mixes.
🥩 No protein jelly or insects are needed. The fungus makes all the protein the queen and brood need.
Plan ahead for the UK winter. Bramble often keeps its leaves through a mild winter, and box stays green all year. Find a clean, pesticide-free source before the cold months arrive.
Keep Mites Out of Your Colony
Blood-sucking mites are common in ant keeping, not rare. They usually arrive with bird seed from local shops and off-licences, dried mealworms, or live food from pet shops and online sellers, where about half carries mites.
Leafcutters don't need any of those foods. Buy ant food only from established, reputable ant-keeping suppliers. At Best Ants UK we clean our foods before dispatch, check every colony twice a month, and check each one again before it leaves us.
Every so often, look at your queen with a magnifying glass. Tiny white or reddish specks on her joints and legs, along with ants dying fast, are a warning sign of blood-sucking mites.
Stopping Escapes
Leafcutters explore every corner, and they climb well. Paint a band of 👉 PTFE Fluon escape barrier around the top inner edge of the outworld lid. The ants slip off it and can't climb out.
PTFE wears off as the ants keep testing the same spots. For up to about 100 ants, reapply it roughly every 4 weeks. For 300 to 500 ants or more, reapply it about every 2 weeks. Never shake the bottle; roll it gently in your hands.
Winter Care
Atta sexdens has no winter rest at all. Keep the fungus chamber at 24 to 27°C and keep the fresh leaves coming through the whole winter.
The heating system matters most from autumn to spring. Never put ants in a fridge, shed or garage, and avoid any abrupt temperature change. Cold doesn't kill at once: the ants get sick and die over the following days.
Can I Release My Leafcutter Ants?
No. A colony raised indoors won't survive outside. If you ever can't keep your colony any more, 👉 visit our ant adoption page and let us know. We'll see whether we can take it in.
Frequently Asked Questions | FAQ
Is Atta sexdens a good beginner ant?
No. Atta sexdens is for experienced keepers only. Warmth, very high humidity in the fungus chamber and a daily supply of fresh leaves must always be right. A beginner species such as Lasius niger or Messor barbarus is a far better first colony.
What does Atta sexdens eat?
Fresh leaves, flowers and small pieces of fruit, which the workers feed to their fungus garden. The fungus then feeds the colony. Bramble, raspberry, rose, box, elder and lime (linden) leaves are all good choices.
Why can't I keep an Atta sexdens queen on her own?
Because the colony lives on its fungus garden, and a lone queen can't tend it. Leafcutters are only ever kept as a colony: the queen, her workers and their fungus together.
What temperature does Atta sexdens need?
Keep the fungus chamber at 24 to 27°C all year, and the outworld at 21 to 28°C. Most UK homes need an Advanced Heating System under one quarter of the fungus chamber, set to 25°C.
Does Atta sexdens hibernate?
No. It is a tropical ant with no winter rest. Keep it warm, humid and supplied with fresh leaves through the whole year.
How big does an Atta sexdens colony get?
In the wild, a mature colony can reach 5 to 8 million ants, with a queen that can live for about 15 years. In an ant farm it grows step by step, so plan for more space as it grows.
Does Atta sexdens bite or sting?
They have no sting, but the big soldiers can bite hard with their sharp jaws. Never handle them, and always keep the outworld lid closed.
Ready for Your Own Leafcutter Farm?
👉 Find Atta sexdens colonies in our shop and check availability, and watch a giant queen's fungus farm grow.
Print this guide and keep it next to your leafcutter setup. 👉 Keep the essentials close and explore all our free ant care sheets.
