Camponotus japonicus

Japanese Carpenter Ant

🐜 At a glance

Origin: 🌏 East Asia — Japan, Korea, China and Mongolia
Keeping level: Beginner — calm, large and long-lived. No sting, but majors can bite
Queen: 15–18mm, glossy black
Workers: 6–9mm minors; 9–14mm majors
Colony form: Single queen; 5,000+ workers
Nest temperature: 24–28°C during the growing season
Nest humidity: 50–70%
Workers before moving into a nest: 3+ minimum, 5+ recommended
Winter: Natural winter rest — never below 15°C, 17°C+ recommended

📖 About this species

A calm, glossy black giant from East Asia and one of the best display species in the hobby. Growth is slow at first, then the colony expands strongly year after year. Workers forage mainly by day, and the clear difference between minors and majors makes them rewarding to watch. In our experience most carpenter ant queens eat their eggs during transport: completely normal for Camponotus (and only Camponotus), and the queen lays again within 2 to 3 months of settling in.

📦 When your ants arrive

⚠️ MOST IMPORTANT: leave the parcel completely unopened, exactly as it arrived, at room temperature for 5 hours. The ants must adjust to your home’s temperature gradually — 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 (test tube still in its tin foil and wrapping) in a quiet spot — in daylight, never direct sunlight — away from vibration and daily household activity.
😴 Give the colony 4 to 5 days of complete rest. The ants were fed before dispatch and need nothing from you during this time. Assemble and water the nest while you wait.
Still workers or a motionless queen after delivery are almost always delivery stress. Check the antennae: moving antennae means she is fine. Almost all recover within 4 to 5 days (a little longer for bigger queens).
Do not remove the black divider inside the test tube (between the two cotton stoppers) — it keeps the ants safe in transit. It has a hole, and the queen and all workers pass through it without any issue.
👑 A queen on her own: keep her test tube wrapped in its tin foil, undisturbed, and feed her once a week — a tiny drop of protein jelly, about half a grain of rice, on a small flat piece of tin foil placed inside the tube next to the dry cotton stopper. In our experience a fed queen is stronger and her brood develops about 30% faster.

🏠 Moving into the ant farm

Keep the colony in its test tube until it has at least 3 workers — 5 or more is recommended. Carpenter ant workers are big and capable from the start. A queen bought on her own, with no workers yet, stays in her test tube until she has 15+ workers: a lone founding queen needs a strong workforce before a bigger space.
Connect the test tube to the nest with the delivery tin foil still on and leave it for 14 days. Then slide the foil back about 1mm every day until the tube is fully exposed to daylight.
If the ants have not moved in 2 days after the tube is fully exposed, wrap the foil back on, wait another fortnight and repeat the whole process — patience is the key. Moving in happens on the ants’ own time: anywhere from a couple of days to 6 months.
The red filter and black cover stay on the nest at all times — it is pitch dark inside. The black cover can come off once a day for 2 to 3 minutes (ideally at night); the red filter once a week for 2 to 3 minutes.
☀️ 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, strong smells such as the kitchen, and busy walkways. Keep a steady room temperature.

🍯 Feeding

🍯 Camponotus love honey — our organic ant honey (lab-tested at 81% carbohydrate) or Best Ants UK Ant Nectar (90% dextrose) is their favourite energy source. Never sugar water.
🥩 Protein for the queen and brood: NextSwarm Cricket Mash is especially efficient for carpenter ants and larger colonies; Best Ants UK Protein Jelly works too. Keep protein jelly in the fridge once opened.
Feed twice a week, small amounts, in the outworld only. Remove leftovers after 2 days to prevent mould.
🦗 Live food (mealworms, crickets, locusts) is only for established colonies, never small ones. All bought live food carries tiny mites that can destroy a colony, so always scald it first: hold it with tweezers in just-boiled water (no longer bubbling) for 10 to 15 seconds, then chop it in half and serve on a small tin foil tray.

💧 Watering the nest

💧 Use distilled or purified water only — never tap, rainwater or bottled mineral water, even boiled. They carry minerals and microbes that turn a nest green with mould. A litre of distilled water costs a few pounds and lasts over a year.
Water the nest with the pipette provided: pour slowly, a few drops at a time, through the watering hole, and stop as soon as 1 or 2 drops appear inside the nest — that is how you know it is done correctly. More than that is too much.
Once a week is usually right — slightly more in summer, less in winter. Never water the outworld.

🌡️ Temperature and winter

Camponotus japonicus has an internal biological clock: from around the end of November to the end of February the colony slows right down on its own, whatever you do.
This is an Asian species: never let it drop below 15°C, whether it is resting or not — 15°C is the bare minimum, and we recommend 17°C or above. Let it rest at normal room temperature and never use a fridge, shed or garage. Reduce food to about half and keep the nest watered.
From March onward, normal feeding resumes as the colony wakes; 24–28°C in the nest gives the best growth. In a UK home that means a heating mat for most of the year.

🤩 Did you know?

It is one of the largest ants in Japan and is often seen marching along pavements and park paths.
In the wild it nests underground without any visible mound — just a small entrance hole.

⭐ Golden rules | Never break these

🚫 Never put ants in a fridge, and never expose them to abrupt temperature changes. Cold does not kill a colony instantly — the ants get sick and die over the following days — and prolonged cold near freezing damages the sperm a queen stores from her nuptial flight, so she may never lay fertile eggs again.
🚫 Never use gel ant farms, Ytong or concrete nests, or DIY nests.
🚫 Never use tap, rain or mineral water, even boiled.
🚫 Never move a colony into a nest too early, and never tip or shake ants out of their tube.
🚫 Never disturb the colony with tapping or handling — vibration stresses the queen and she can stop laying or eat her eggs.
☀️ Never keep the farm in the dark: ants need daylight for their circadian rhythm. Daylight yes — direct sunlight never.
🚫 Never release this species into the wild — a colony raised in an ant farm would not survive. If you can no longer keep it, visit our ants adoption page and ask us whether we can adopt it.

🛒 Recommended for this species

📚 These care notes cover the essentials only. Please read the full ant farm setup guide and our carpenter ant guide from A to Z. Questions? Message us through our contact form and we will be happy to help. 💚

Written and reviewed by the Best Ants UK team, keeping ants since 1997.