How to Care for Lasius americanus | The Woodland Lasius Ant Guide
Photo: Alex Abair, via Wikimedia Commons, licensed under CC BY 4.0.
Lasius americanus is a small, dark brown ant of shady North American woodland, where it lives under logs, stones and leaf litter. Known as the woodland Lasius ant, it is a close cousin of our own black garden ant.
It is hardy, busy and fascinating to watch, and a healthy colony grows into the thousands. This guide explains Lasius americanus care step by step, from a single queen to a thriving colony.
Lasius americanus is a North American ant, and Best Ants UK does not sell it. It may be illegal or impossible to import to the UK, and we don't encourage importing ants from abroad. This guide is for keepers where the species is native, and for anyone curious about it.
We have kept ants since 1997, and the care rules here are the same ones we use for our own colonies every day.
👉 In a hurry? Download our free Lasius americanus care sheet (PDF) or open the Lasius americanus care sheet page for the key facts at a glance.
Lasius americanus at a Glance
Also known as: the woodland Lasius ant, large-eyed Lasius or woodland fuzzy ant
Origin: North America, from southern Canada to northern Florida, and the mountains of the south-western USA and Mexico
Keeping level: Beginner
Queen: about 7 to 9mm, dark brown to black
Workers: about 3 to 4mm, all one size, dark brown to black
Colony: starts with one queen, thousands of workers when mature
Nest temperature: 21 to 25°C
Nest humidity: 50 to 70%
Workers before moving into a nest: 10 minimum, 15 to 20 recommended
Winter: a natural winter rest, never in a fridge
Escape risk: small workers, so a PTFE barrier is a must
Meet the Woodland Lasius Ant
In the wild, Lasius americanus is a forest ant. It prefers well-shaded woodland, where it nests in the soil, inside and under rotting logs and stumps, under stones and in deep leaf litter.
Its relatives, Lasius niger and Lasius neoniger, love open, sunny ground instead. Lasius americanus also has slightly larger eyes, which gives it one of its common names.
For many years American keepers called it Lasius alienus, a European ant that looks almost identical. Scientists have since confirmed that the American ant is a species of its own.
Like most Lasius, it is a farmer. The workers look after aphids, scale insects and root bugs for their sweet honeydew, sometimes building little shelters of soil and plant bits around plant stems to protect them. They also hunt and scavenge small insects.
New queens and males fly mostly in August, on warm days. A mated queen founds her colony alone. In the wild, big old colonies sometimes have several queens, but in an ant farm keep one queen per colony.
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, with no food. A good supplier feeds the ants before dispatch. 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.
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. The workers are small, and moved too early they often abandon the queen in the bigger space, so the colony can fail.
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.
Be patient. The brood takes around 6 to 8 weeks from egg to worker. Keepers report dozens of workers in the first year, hundreds in the second and 1,000 or more after that.
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. 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, 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 no more than once a month.
The Best Ant Farm for Lasius americanus
Small Lasius workers squeeze through tiny gaps, so their home must be well made and escape-proof. A young colony feels safest in a small nest it can fill.
👉 Our top pick is the A7 Plus ant farm kit. Its pre-installed digital meter shows nest temperature and humidity at a glance, which makes watering and heating far easier and keeps mistakes to a minimum.
Place the ant farm in normal daylight, never direct sunlight. Even a woodland ant needs a normal day and night rhythm. 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 21 to 25°C. In a warm home, normal room temperature is enough. Avoid overheating: this shade-loving ant does not like extreme heat.
In a cool home, though, where the room stays around 20°C or below, the brood takes far longer to develop. 👉 There, an Advanced Heating System Small 4W set to 24°C helps the colony thrive.
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
Keep the nest humidity at 50 to 70%, with the area near the watering hole a little damper. 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.
Feeding Your Woodland Lasius Ants
Woodland Lasius ants have a real sweet tooth, just like their aphid-farming cousins. 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. Both are far better than sugar water or home-made mixes. Offer small drops, as tiny workers can get stuck in a big one.
🥩 For the queen and brood, give 👉 Protein Jelly or 👉 Cricket Mash. 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.
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 and off-licences, dried mealworms (useless as ant food), and live food from pet shops or online, where about half 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 and check every colony twice a month.
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
Small Lasius workers explore every corner, and most escapes happen right after feeding. 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
Woodland Lasius ants come from places with cold winters, and they have a natural winter rest. Their development slows down from late autumn whatever you do, because their biological clock can't be tricked. We never hibernate queens in their first year.
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 avoid any abrupt temperature change.
Without a hibernation unit, keep the colony at room temperature all winter. Feed less, 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 Ants?
Never. Lasius americanus is not a UK ant, and a colony raised indoors won't 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 Lasius americanus good for beginners?
Yes. It is a hardy, easy-going species, very like the UK black garden ant. The workers are small, so keep the colony in its test tube until it has at least 10 workers and use a PTFE barrier.
Can I buy Lasius americanus in the UK?
Best Ants UK does not sell Lasius americanus. It is a North American ant, and it may be illegal or impossible to import to the UK. UK keepers can start with its close relative, the black garden ant Lasius niger.
Is Lasius americanus the same as Lasius alienus?
No. For many years American keepers called it Lasius alienus, a European ant that looks almost the same. Scientists have since confirmed it is a separate species found only in North America.
How many workers before moving Lasius americanus into a nest?
At least 10 workers, and 15 to 20 is even better. The workers are only about 3 to 4mm long, so a smaller colony is easily lost in an ant farm.
What temperature do Lasius americanus need?
Keep the nest at 21 to 25°C. In a cool home where the room stays around 20°C or below, an Advanced Heating System set to 24°C under one quarter of the nest helps.
Do Lasius americanus hibernate?
They have a natural winter rest. A full hibernation is only safe at a steady 10°C in a specialised hibernation unit, never a fridge, shed or garage. Otherwise keep them at room temperature; they slow down anyway. We never hibernate queens in their first year.
What do Lasius americanus eat?
They love sugars. Give organic honey or Ant Nectar for energy, and Protein Jelly or Cricket Mash for the queen and brood, twice a week in the outworld only.
Ready for Your Own Lasius Colony?
A woodland Lasius colony can grow to thousands of busy workers. When yours outgrows its first nest, 👉 the A6 ant farm kit with meter gives a big colony more room, with a digital meter to keep watering and heating simple.
Print this guide and keep it next to your ant farm, so the essentials are always close. 👉 Explore all our free ant care sheets.
