How to Care for Formica rufa | The Red Wood Ant Guide for Keepers
Updated: 3 days ago
Anyone who has walked through a British pine wood has seen their work: huge domes of needles, alive with ants. Formica rufa, the red wood ant, is one of the most famous ants in the world, and keeping a colony is a real adventure.
This guide explains Formica rufa care step by step, including the one thing that makes them different from most ants: how a new colony begins.
We have kept ants since 1997, and everything here comes from our own colonies and the care rules we use every day.
👉 In a hurry? Download our free Formica rufa care sheet (PDF) or open the Formica rufa care sheet page for the key facts at a glance.
Formica rufa at a Glance
Also known as: the red wood ant, southern wood ant or horse ant
Origin: UK native woodland ant, found across Europe and Russia
Keeping level: Advanced
Queen: 10 to 12mm, reddish brown with a darker head and gaster (back end); can live 10 to 15 years
Workers: 4 to 10mm, in many different sizes
Founding: the queen needs workers of another Formica species to start a colony
Colony: starts with one queen; wild colonies can hold dozens of queens
Nest temperature: 22 to 25°C
Nest humidity: 50 to 60%, never higher
Workers before moving into a nest: 10 minimum, 15 to 20 recommended
Winter: hibernation optional
Escape risk: fast and determined, so a PTFE barrier is a must
Meet the Red Wood Ant
In the wild, red wood ants build big mounds of pine needles, twigs and soil in woodland clearings and along sunny forest edges. One mound can be home to hundreds of thousands of workers, and neighbouring mounds can link up into huge networks.
They are mighty hunters and help control many pest insects in the woods. They also farm aphids high in the trees for their sweet honeydew.
They have no sting, but they bite and spray formic acid. Some birds, such as jays, even sit on wood ant nests and let the ants spray their feathers, a habit called "anting" that is thought to help clean off parasites.
How a Red Wood Ant Colony Begins
This is the most important thing to know before you buy. A red wood ant queen can't start a colony on her own, the way a Formica fusca or Lasius niger queen can.
She is a temporary social parasite. In nature, a young queen often returns to a big wood ant nest. Otherwise she sneaks into a nest of another Formica species, such as Formica fusca, and those host workers raise her first brood as if it were their own.
As her own red wood ant workers hatch, they slowly take over the work, and the host workers die out over time. The nest becomes a pure wood ant colony.
What this means for you: never try to start with a lone queen. Always choose a colony that already has workers.
When Your Ants Arrive
The most important step: leave the parcel completely unopened, exactly as it arrived, at room temperature for 5 hours. The ants must adjust to your home's temperature slowly, because abrupt temperature changes make ants seriously unwell.
After the 5 hours, check the queen is safe and sound. Then leave the colony in its original packaging, with the test tube still in its tin foil and wrapping, somewhere quiet and still, away from daily household activity.
Give the colony 4 to 5 days of complete rest. The ants were fed before dispatch, so they need nothing from you. Use this time to set up and water the nest. 👉 Our step-by-step ant farm setup guide shows you how.
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 big queen like this one can take a little longer.
Life in the Test Tube
Keep the colony in its test tube until it has at least 10 workers. 15 to 20 is even better. Moved earlier, the workers often abandon the queen in the bigger space, and the colony can fail.
A young queen with only a few workers still needs a little extra food. Once a week, give her a tiny drop of protein jelly, about half a grain of rice, on a small flat piece of tin foil inside the tube, next to the dry cotton stopper.
In our experience a well-fed queen raises new workers faster, and the colony does far better afterwards. Keep the tube wrapped in its foil and disturb it as little as possible.
Moving Into the Ant Farm
When the colony is ready, connect the test tube to the nest with the delivery tin foil still on. Leave it like that for 14 days.
Then slide the foil back about 1mm every day until the tube is fully exposed to daylight. If the ants haven't moved 2 days later, wrap the foil back on, wait another fortnight and repeat. Moving in can take from a couple of days to 6 months.
Once the colony has moved, leave the old test tube connected for at least another 14 days, as ants sometimes leave brood behind.
The red filter and black cover stay on the nest all the time. You can lift the black cover once a day for 2 to 3 minutes, ideally at night, and take the red filter off once a week for 2 to 3 minutes. Take colony photos once a month at most.
The Best Ant Farm for Formica rufa
Red wood ants spray formic acid when disturbed. In a stuffy, sealed box it builds up and harms the colony, so their home must be well ventilated, roomy and tall enough for them. Never block the air holes.
👉 Our top pick for wood ants is the natural eco ant farm. It is airy and natural, and the ants can dig and build in it as they would in the wild. No connection is needed: take out the cotton stopper and place the test tube inside.
👉 For a young colony, the A7 Plus ant farm kit works well too. Its pre-installed digital meter shows nest temperature and humidity at a glance, which matters with a species that dislikes damp. If you already have your ants, choose the Nest + Outworld option.
Place the ant farm in normal daylight, never direct sunlight. Avoid windows, radiators and heaters, vibrating surfaces, speakers and TVs, and rooms with strong smells such as the kitchen.
Temperature and Heating
Keep the nest at 22 to 25°C. Wood ants gather their brood in the warmest part of the mound, so a gentle warm spot really helps.
In a cool home, where the room stays around 20°C or below, the colony won't thrive and the brood takes far longer to develop. 👉 There, an Advanced Heating System Small 4W set to 24°C makes a big difference.
The heat mat goes under one quarter of the nest only, on the side opposite the watering area, so the ants can choose their spot. Never heat the whole nest.
In the outworld, aim for about 18°C overnight up to 28°C by day. By day it should ideally match the nest or be a degree or two cooler. If the nest is heated, warm the outworld too, because a big gap confuses the ants.
Water and Humidity
Red wood ants like it drier than most ants. Keep the nest humidity at 50 to 60%, and never higher, or the setup goes mouldy. Use distilled or purified water only. Never use tap water, rainwater or bottled mineral water, even boiled.
Water the nest with the pipette provided. Pour slowly, a few drops at a time, through the watering hole. Stop as soon as 1 or 2 drops appear inside the nest. That is how you know it is done correctly.
Water about once a week, a little more in summer and a little less in winter. With a meter, simply water when the nest humidity drops below 50%.
In the natural eco ant farm, water the surface of the substrate instead, 1 to 3ml at a time, and wait at least a day before adding more.
Never water the outworld. Keep it dry, at about 50% humidity, like an average UK home.
Feeding Your Red Wood Ants
Wood ants are big hunters, and a growing colony has a huge appetite. Feed twice a week, in small amounts, in the outworld only. Remove leftovers after 2 days to stop mould.
🥩 For the queen and brood, give 👉 Protein Jelly or 👉 Cricket Mash. Keep protein jelly in the fridge at all times.
🍯 For energy, give our 👉 organic ant honey or 👉 Ant Nectar, which has even more carbohydrates than honey. Both are far better than sugar water or home-made mixes.
Serve food on a small piece of tin foil or in a 👉 small feeding dish, so leftovers are easy to lift out.
Live food, such as crickets or locusts, is only for big, established colonies, never small ones. Always scald it first: wearing gloves, hold it with tweezers in just-boiled water (above 90°C, no longer bubbling) for 10 to 15 seconds.
Then cut it in half and serve it in the outworld.
Keep Mites Out of Your Colony
Blood-sucking mites are one of the biggest dangers for any ant colony, and they are not rare. They often arrive with bird seed from local shops, dried mealworms, and live food bought from pet shops or online. In our experience about half of that live food carries mites.
Buy ant food only from established, reputable ant-keeping suppliers. At Best Ants UK we clean our foods in several ways 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
Red wood ants are quick and determined, so escape prevention is a must. 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 a small colony of 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, because it foams. Roll it gently in your hands instead.
Winter Care
Hibernation is optional for red wood ants in captivity. They can stay at normal room temperature all winter. We never hibernate queens in their first year.
Their development still slows down from late autumn, whatever the temperature. Their biological clock can't be tricked.
A full hibernation is only safe at a steady 10°C, roughly from December to the end of March. That needs a specialised hibernation unit with precise temperature control. Never use a fridge, shed or garage, and never make abrupt temperature changes.
Feed less in winter, but never guess. At 17 to 22°C, give about a third of the summer amount. At 22 to 26°C, give about half. In full hibernation, give fresh water only and no food.
Can I Release My Red Wood Ants?
We don't advise releasing a colony raised indoors, as it is unlikely to survive outside. If you 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 Formica rufa good for beginners?
Not really. Red wood ants are fast, bold and hungry, and they need a roomy, well-ventilated setup and careful watering. They suit keepers with some experience. For a first colony, an easier species such as Formica fusca is a better start.
Can a Formica rufa queen start a colony on her own?
No. A wood ant queen can't raise her first workers alone. In nature she moves into a nest of another Formica species, such as Formica fusca, and those workers raise her first brood. That is why you should always choose a colony that already has workers.
Do red wood ants sting?
They have no sting, but they bite and spray formic acid. The acid is harmless to people. As with every ant, never handle them.
How many workers before moving Formica rufa into a nest?
At least 10 workers, and 15 to 20 is even better. Moved earlier, the workers often abandon the queen in the bigger space.
What temperature and humidity do red wood ants need?
Keep the nest at 22 to 25°C and the humidity at 50 to 60%, never higher, or the setup goes mouldy. In a cool home, an Advanced Heating System set to 24°C under one quarter of the nest helps.
Do Formica rufa need to hibernate?
Hibernation is optional in captivity. They can stay at room temperature all winter. A full hibernation is only safe at a steady 10°C, in a specialised hibernation unit with precise temperature control, never a fridge, shed or garage.
How big does a Formica rufa colony get?
Wild mounds can hold dozens of queens and hundreds of thousands of workers. In captivity, a suitable setup can house up to around 1,000 workers for a few years.
Start Your Own Red Wood Ant Colony
👉 Find Formica rufa colonies in our shop, and bring a piece of the British woodland into your home.
Print this guide and keep it next to your ant farm. 👉 Keep the essentials close and explore all our free ant care sheets.
