How to Care for Camponotus japonicus | The Japanese Carpenter Ant Guide
Updated: 3 days ago
Big, glossy black and wonderfully calm, Camponotus japonicus is one of the best display ants you can keep. The Japanese carpenter ant is one of the largest ants in Japan.
Its colonies start slowly, then grow stronger every year, with small workers and huge majors side by side. This guide explains Camponotus japonicus care step by step, from the day your parcel arrives.
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 Camponotus japonicus care sheet (PDF) or open the Camponotus japonicus care sheet page for the key facts at a glance.
Camponotus japonicus at a Glance
Also known as: the Japanese carpenter ant
Origin: East Asia: Japan, Korea, China, Mongolia and the Russian Far East
Keeping level: Advanced beginner
Queen: 14 to 17mm, glossy black with a strong thorax
Workers: 6 to 14mm, in several sizes, black
Colony: one queen, around 1,000 ants in the wild
Nest temperature: 24 to 28°C in the growing season
Nest humidity: 50 to 70%
Workers before moving into a nest: 3+ is a must, 5+ recommended
Winter: a natural rest, never below 15°C, 17°C recommended
Escape risk: strong climbers, so a PTFE barrier is a must
Meet the Japanese Carpenter Ant
In the wild, Camponotus japonicus lives in open grassland, parks and along paths across East Asia. It nests underground without any visible mound, so all you see is a small entrance hole.
The workers come in several sizes. Small minors run errands and care for the brood, while the big-headed majors carry heavy food and guard the nest. Seeing both together is a big part of the fun.
Workers forage mainly by day, so there is lots to watch. Young queens fly out from May to June, then seal themselves away to raise their very first workers.
Here is a strange fact: Japanese carpenter ants are the host of a parasitic ant, Polyrhachis lamellidens, whose queens sneak into their nests and take over.
Japanese carpenter ants have no sting, although the big workers can give a nip. Growth is slow at first, then the colony expands strongly year after year.
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.
Put it somewhere quiet and still, away from daily household activity. Normal daylight is fine, but never direct sunlight.
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 exactly 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 big queens can take a little longer.
Life in the Test Tube
Carpenter ant workers are big and capable from the start, so they don't need a huge colony before moving. Keep the ants in their test tube until there are at least 3 workers. That is a must. 5 or more workers is even better.
Don't worry if the queen's eggs have disappeared when the parcel arrives. Most carpenter ant queens eat their eggs during delivery. This is normal for Camponotus, and only Camponotus. She lays again within 2 to 3 months of settling in.
A queen on her own still needs a little 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 fed queen raises her first workers faster, and the queen and colony do far better afterwards. Keep her tube wrapped in its foil and disturb her as little as possible.
If your room is cool in the growing season, warm the tube with a heating cable at the cotton stopper end only. Never lay a test tube on a heat mat.
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. Bit by bit, the tube becomes the bright spot and the dark nest becomes the safe home.
If the ants haven't moved 2 days after the tube is fully exposed, wrap the foil back on, wait another fortnight and repeat the whole process. Moving in happens on the ants' own time: anywhere 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. Ants sometimes leave a little brood behind.
The red filter and black cover stay on the nest all the time, so it is pitch dark inside. 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.
The Best Ant Farm for Camponotus japonicus
Japanese carpenter ants are strong and curious, so their home must be well made and escape-proof. 👉 Our Carpenter Ant Farm Starter Kit is made for carpenter ants, with a nest and its own humidity and temperature meter, an outworld and a watering test tube.
👉 The A7 Plus ant farm kit is another great choice. Its pre-installed digital meter shows the nest temperature and humidity at a glance. If you already have your ants, choose the Nest + Outworld option.
Place the ant farm in normal daylight, never direct sunlight: the sun can overheat a nest within minutes. Avoid windows, radiators and heaters, vibrating surfaces, speakers and TVs, and rooms with strong smells such as the kitchen.
Temperature and Heating
From March to November, the growing season, keep the nest at 24 to 28°C for the best growth. Camponotus japonicus is an Asian species: never let it drop below 15°C, at any time of year, and we recommend 17°C or above.
Most UK homes are cooler than 24°C for much of the year. 👉 The Advanced Heating System Small 4W holds the nest steady with its digital thermostat. Set it to 24°C.
The heat mat goes under one quarter of the nest only, on the side opposite the watering area. The ants can then pick the spot they like best. 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
Keep the nest humidity at 50 to 70%. Use distilled or purified water only. Never use tap water, rainwater or bottled mineral water, even boiled: they cause mould and fungus, which is deadly for ants.
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%.
Never water the outworld. Keep it dry, at about 50% humidity, like an average UK home. Carpenter ants should never have open water: give them a watering test tube in the outworld instead, never a water dispenser.
Feeding Your Japanese Carpenter Ants
Carpenter ants have a real sweet tooth, and a growing colony needs plenty of protein too. Feed twice a week, in small amounts, in the outworld only. Remove leftovers after 2 days to stop mould.
🍯 For energy, give our 👉 organic ant honey or 👉 Ant Nectar, which has even more carbohydrates than honey. Honey and Ant Nectar are far better than sugar water or home-made mixes.
🥩 For the queen and brood, 👉 Cricket Mash is the more efficient protein for carpenter ants. 👉 Protein Jelly works well too. Keep protein jelly in the fridge at all times.
Serve food on a small piece of tin foil or in a 👉 small feeding dish, so leftovers are easy to lift out. Now and then, a rice-grain-sized piece of peeled grape or banana makes a nice treat.
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 only, 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 (which are useless as ant food anyway), and live food from pet shops or online.
In our experience about half of all bought live food carries mites, so where you buy matters.
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
Japanese carpenter ants are strong climbers, 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
Camponotus japonicus has a built-in biological clock. From around the end of November to the end of February, the colony slows right down on its own, whatever you do. The biological clock can't be tricked.
Let it rest at normal room temperature. Never let it drop below 15°C, which is the bare minimum for this Asian species, and we recommend 17°C or above. If your home gets colder than that, keep the heater on.
Never put ants in a fridge, shed or garage, and avoid any abrupt temperature change. Keep watering the nest as usual.
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, still twice a week. From March, normal feeding returns as the colony wakes up.
Can I Release My Ants?
No. A colony raised indoors won't survive outside, and this is not a UK species. 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 Camponotus japonicus good for beginners?
It is a species for advanced beginners rather than complete newcomers. The ants are calm, large and hardy, but they need warmth in the growing season, a winter that never drops below 15°C and a patient keeper.
How many workers does Camponotus japonicus need before moving into a nest?
At least 3 workers is a must, and 5 or more is recommended. Carpenter ant workers are big and capable from the start, so they settle into an ant farm sooner than smaller species.
What temperature do Camponotus japonicus need?
Keep the nest at 24 to 28°C from spring to autumn for the best growth. As an Asian species, it must never drop below 15°C, resting or not, and we recommend 17°C or above.
Do Camponotus japonicus hibernate?
They don't need a cold hibernation. From around the end of November to the end of February the colony slows down on its own. Let it rest at room temperature, never below 15°C, ideally 17°C or more, and never in a fridge, shed or garage.
Why did my Camponotus japonicus queen eat her eggs?
Most carpenter ant queens eat their eggs during delivery. This is normal for Camponotus, and only Camponotus. Once she settles in, she lays again within 2 to 3 months.
What do Camponotus japonicus eat?
Organic honey or Ant Nectar for energy, and Cricket Mash or Protein Jelly for the queen and brood. Feed twice a week, in the outworld only, and remove leftovers after 2 days.
Do Japanese carpenter ants sting?
No, they have no sting. The big workers can give a nip with their jaws. As with every ant, never handle them.
Ready to Start Your Japanese Carpenter Ant Colony?
👉 Find Camponotus japonicus queens and colonies in our shop, and watch a calm giant grow stronger year after year.
Print this guide and keep it next to your ant farm. 👉 Keep the essentials close and explore all our free ant care sheets.
