How to Care for Trachymyrmex septentrionalis | The Fungus-Gardening Ant Guide
Photo: "Northern Fungus Farming Ant - Trachymyrmex septentrionalis" by Christina Butler, via Wikimedia Commons, licensed under CC BY 2.0.
A tiny farmer from the pine barrens: Trachymyrmex septentrionalis is the most northern fungus-growing ant in the world. The workers gather bits of dead plants and caterpillar droppings to feed a fungus garden, and the fungus feeds the colony.
It is a small, calm, slow-moving cousin of the leafcutter ants, and watching it tend its spongy white garden is fascinating. This guide explains Trachymyrmex septentrionalis care step by step, from arrival to a healthy fungus garden.
Trachymyrmex septentrionalis is a North American ant, and Best Ants UK does not sell it. North American ants may be illegal or impossible to import into the UK, and we never encourage importing ants. This guide is for keepers where it is native, and for anyone curious.
We have kept ants since 1997. Fungus-growing ants are an expert species, so read this guide from A to Z before you begin.
👉 In a hurry? Download our free Trachymyrmex septentrionalis care sheet (PDF) or open the Trachymyrmex septentrionalis care sheet page for the key facts at a glance.
Trachymyrmex septentrionalis at a Glance
Also known as: the northern fungus-gardening ant
Origin: eastern USA, from Texas and Florida north to Illinois, Ohio and Long Island in New York
Sold by Best Ants UK: no, it is a North American species
Keeping level: Expert
Queen: 5 to 7mm, reddish brown
Workers: 3 to 4.5mm, yellowish to reddish brown, bumpy and spiny, all one size
Colony: one queen, a few hundred to a few thousand ants
Main food: oak catkins, fresh buds, tender shoots, fresh petals and soft leaves for the fungus garden
Fungus chamber temperature: 22 to 25°C, never above about 28°C
Fungus chamber humidity: 80 to 90%
Waste area: dry, about 30 to 40% humidity
Moving in: straight into the ant farm after up to 5 hours of settling; always a whole colony with its fungus, never a lone queen
Winter: a natural winter rest, never a fridge
Meet the Northern Fungus-Gardening Ant
Septentrionalis means "northern". In the wild this ant lives on sandy, well-drained soil in pine barrens, open oak and pine woodland and sandy clearings. Its nest entrance is marked by a neat crescent-shaped heap of soil.
Under the ground, older colonies have several chambers, each holding a spongy fungus garden that hangs from the ceiling. The fungus forms small food bodies that the ants harvest for the queen and brood (the eggs, larvae and pupae).
Unlike true leafcutters, the workers rarely cut fresh leaves. They collect caterpillar droppings (frass), oak catkins, flower parts, seeds and other dead plant bits from the ground, and use them as compost for the fungus.
In winter the colony rests and the fungus garden shrinks. Mating flights happen in summer, from June to August, often after heavy rain. Each young queen carries a tiny piece of fungus from her home nest to start her own garden.
When Your Ants Arrive
Fungus-growing 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. The ants 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 move the colony into its ant farm setup straight away. The ants 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 a little of their food, such as oak catkins and fresh petals, as soon as the ants are in their setup. The fungus garden needs it 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.
Don't worry if part of the fungus garden looks damaged. Losing up to a third of the fungus in transit is normal. A small healthy piece is enough: with the right warmth, humidity and food, the ants rebuild it.
Always a Colony, Never a Lone Queen
Fungus-growing ants 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 food coming.
The Right Setup for Trachymyrmex septentrionalis
Best Ants UK doesn't offer an ant farm for fungus-growing ants. Experienced keepers build a setup with three connected areas: a warm, humid fungus chamber, a foraging area (outworld) where you put the food, and a separate dry waste area.
The fungus chamber needs a digital humidity and temperature meter, because with fungus growers the humidity must be right every single day. Plan for more room in all three areas as the colony grows.
The ants carry used plant material, 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.
Healthy fungus is white and spongy. If it turns yellow or orange, it is too wet; if it shrinks and darkens, it is too dry.
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
Keep the fungus chamber at 22 to 25°C. Steady conditions matter more than anything: the fungus reacts badly to big swings. Above about 28°C it suffers, so too much heat is as dangerous as too little.
In a warm home, no heating may be needed. Never put a heat mat or heating cable on or under the fungus chamber: the warm wall against cooler room air causes condensation, the droplets soak the fungus garden, and it collapses or turns mouldy. If your home drops below 22°C, warm the room itself, or an insulated box around the whole setup, to 22 to 25°C.
Keep the outworld at about 18°C overnight up to 28°C by day. By day it should ideally match the fungus chamber or be a degree or two cooler. Warming the room or an outer box keeps the whole setup even.
Water and Humidity
Keep the fungus chamber at 80 to 90% humidity. If the fungus dries out, the colony starves. 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%. Fungus growers need much more humidity than most ants, so check the meter every day. Aim for humid, not wet: heavy condensation means too much water.
Never water the outworld; keep it at about 50% humidity. Keep the waste area dry, at about 30 to 40%. Keep the outworld well ventilated, so the food and waste stay dry and don't go mouldy.
Feeding Your Fungus Garden
🌸 These ants eat only their fungus, and you feed the fungus every day. Its main food is oak catkins (fresh, or frozen and thawed in winter), fresh tender tree shoots and small flower buds. Fresh, pesticide-free rose petals and soft green leaves such as bramble and oak are main foods too.
Oat flakes, polenta and dried petals are snacks only: offer them now and then, in small amounts. They soak up moisture and spoil, and a fungus fed only on dry food slows down or dies back. Our dried Dandelion Leaves, Rose Petals and Blue Mallow Flowers are safe as occasional extras.
Put the food on a piece of tin foil or in a 👉 small feeding dish in the outworld, a little at a time, so there is always something to collect. Remove anything that goes soggy or mouldy at once, and take out leftovers after 2 days.
Only use material free from pesticides, chemicals and road dirt: even a trace can destroy the fungus garden. Every colony has its favourites, so try small amounts of each food and watch what the workers carry in.
🍯 Now and then, a tiny drop of our 👉 organic ant honey or 👉 Ant Nectar on tin foil gives the workers extra energy. Both are far better than sugar water or home-made mixes.
🥩 These ants don't need protein jelly or insects. Their fungus makes the protein the queen and brood need.
Keep Mites Out of Your Colony
Blood-sucking mites are a threat to every ant colony, and they are not rare. They often arrive with bird seed from local shops and off-licences, dried mealworms, and live food from pet shops or online, where about half carries mites.
Fungus growers 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 colony again before it leaves us.
Now and then, look at your queen with a magnifying glass. Tiny white or reddish specks on her joints and legs, together with ants dying fast, are a warning sign of blood-sucking mites.
Stopping Escapes
Trachymyrmex workers are slow and calm, but they climb well and are small. 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 instead.
Winter Care
Trachymyrmex septentrionalis comes from places with real winters, and most colonies have a natural winter rest.
When the workers stop feeding the fungus for weeks and the garden shrinks into small lumps, the colony is ready for its rest. That is normal, because its biological clock can't be tricked.
A cool rest of about 8 weeks at a steady 8 to 10°C suits it, but only in a specialised hibernation unit with precise temperature control, cooled down gradually. Keep the fungus chamber humid the whole time. Without a unit, keep the colony at room temperature.
We never rest a queen in her first year. Never put ants in a fridge, shed or garage, and avoid any abrupt temperature change. During a cool rest, give no new food; just keep the humidity right.
Can I Release My Fungus-Growing Ants?
No. A colony raised indoors won't survive outside, and a North American ant doesn't belong in the wild here. 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 Trachymyrmex septentrionalis good for beginners?
No, it is an expert species. The fungus garden needs steady warmth, very high humidity and the right plant material, and it reacts badly to mistakes. Start with a beginner species such as Lasius niger or Messor barbarus first.
Can I buy Trachymyrmex septentrionalis in the UK?
Best Ants UK does not sell Trachymyrmex septentrionalis. It is a North American ant, and it may be illegal or impossible to import into the UK. We never encourage importing ants.
Is Trachymyrmex septentrionalis a leafcutter ant?
Not quite. It is a fungus-gardening ant, a cousin of the leafcutters. Instead of cutting big loads of leaves, it feeds its fungus mostly with oak catkins, caterpillar droppings, buds and flower parts.
What do Trachymyrmex septentrionalis eat?
The ants eat only their fungus. Feed the fungus every day with oak catkins (fresh, or frozen and thawed), fresh tender tree shoots and small flower buds, and fresh, pesticide-free rose petals and soft green leaves such as bramble and oak. Oat flakes, polenta and dried petals are occasional snacks only.
What temperature do Trachymyrmex septentrionalis need?
Keep the fungus chamber at 22 to 25°C, and never above about 28°C. Never heat the nest directly, because it causes condensation that ruins the fungus. In a cool home, warm the room, or an insulated box around the setup, to 22 to 25°C.
Do Trachymyrmex septentrionalis hibernate?
Yes, most colonies have a natural winter rest and the fungus shrinks. A cool rest is only safe in a specialised hibernation unit with precise control. Otherwise keep them at room temperature.
Do Trachymyrmex septentrionalis sting?
No. They have no sting and are calm, gentle ants. Still, never handle them, and keep the outworld lid closed.
New to Ant Keeping?
Fungus-growing ants are a goal for experienced keepers. If you are just starting out, learn the basics with a beginner species first.
👉 Our Angie ant farm starter kit comes with a Messor barbarus colony, harvester seeds and a nest with its own pre-installed humidity and temperature meter. 👉 Explore all our free ant care sheets.
