How to Care for Veromessor andrei | The Andre's Harvester Ant Guide
Photo: Ken-ichi Ueda, via Wikimedia Commons, licensed under CC BY 4.0.
Busy columns of reddish-brown workers clearing little roads through the grass of coastal California: Veromessor andrei is a seed harvester that moves house more often than almost any other ant.
Its queens are unusual too, because they leave their founding chamber to find food. This guide explains Veromessor andrei care step by step, from a hungry founding queen to a thriving seed-gathering colony.
We have kept ants since 1997, and the care rules here are the ones we use every day with our own harvester ants.
👉 In a hurry? Download our free Veromessor andrei care sheet (PDF) or open the Veromessor andrei care sheet page for the key facts at a glance.
Veromessor andrei at a Glance
Also known as: Andre's harvester ant
Origin: coastal California, from southern Oregon to northern Baja California, Mexico
Keeping level: Intermediate
Queen: about 10mm
Workers: about 4.5 to 7mm, mostly one size, usually dark reddish brown with a darker gaster
Colony: tens of thousands of workers when mature
Main food: seeds
Nest temperature: 24 to 28°C
Nest humidity: a steep gradient: seed store bone-dry at 10 to 30%, one damp brood corner at 50 to 60%
Workers before moving into a nest: 10 minimum, 15 to 20 recommended
Winter: a 2 to 3 month rest at about 17 to 18°C, never below 15°C
Water: never open water, a watering test tube only
Meet Andre's Harvester Ant
In the wild, Veromessor andrei lives in open country along the Californian coast range, from the seaside up into mountain valleys. It nests in almost any soil, under a low mound of gravel, soil and seed husks.
Most colonies move their nest every year, and some move up to 10 times in a single year. The colour changes from place to place: pale orange to rusty in the south, dark reddish brown in most areas, and blackish in the Central Valley.
Foragers leave in columns up to about 20 metres long, then spread out to gather seeds one by one. They forage by day when it is cool, at dawn and dusk when it is warm, and at night on warm nights. Neighbouring colonies fight when their columns cross.
The foraging season runs from late March to late autumn. New queens and males fly in the hours after dawn from mid-June to July, with colonies across an area flying at the same time.
Unlike most harvester queens, a young Veromessor andrei queen has few body reserves. She leaves her chamber to find food while she raises her first workers.
Can You Keep Veromessor andrei in the UK?
Veromessor andrei is a North American ant, and Best Ants UK does not sell it. It may be illegal or impossible to bring into the UK, so please never try to import it, and never buy it from anyone offering to ship it here.
This guide is for keepers who live where the species is native and can keep it legally, and for anyone curious about harvester ants.
If you are in the UK and dream of harvesters, our Messor barbarus is a calm, hardy seed harvester, and much of this guide works for it too.
Watch our Messor barbarus care guide, filmed with our own 19-year-old harvester ant 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, somewhere quiet and still, away from daily household activity. Daylight is fine, 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 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 harvester queens 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. The same rule applies to a queen on her own.
Feeding matters even more for this queen, as she forages in the wild while founding. 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.
A few small harvester seeds on the same piece of foil help too. Swap the foil for a fresh one at every feed, so nothing goes mouldy or sprouts in the tube.
In our experience a fed queen raises her first workers faster and does far better afterwards. Keep her tube wrapped in its foil and disturb her 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 Veromessor andrei
👉 For harvester ants we recommend the Angie ant farm starter kit, our harvester ant farm with a pre-installed digital meter. It shows the nest temperature and humidity at a glance, which matters a lot here, as too much water makes seeds sprout.
The A7 Plus ant farm, also with a pre-installed digital meter, is a great choice too. If you already have your ants, choose its 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. A calm, steady setup also stops a restless colony wanting to move.
Temperature and Heating
Keep the nest at 24 to 28°C. Coastal California is milder than the desert, but most UK homes are still too cool for steady growth without gentle heating.
👉 We recommend the Advanced Heating System Small 4W. Its digital thermostat holds a steady warm spot. Set it to 26°C, the middle of the ideal range.
On a horizontal nest such as Angie or the A7 Plus, the heat mat goes under one quarter of the nest. On a vertical nest, it goes under half. Always put it on the side opposite the watering area, so the ants can choose their spot.
The outworld can cool to about 18°C overnight and warm 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.
Water and Humidity
Never keep the whole nest at one humidity. Give it a steep gradient: a bone-dry seed store at 10 to 30%, and one damp brood corner by the watering area at 50 to 60%. Watering the whole nest ruins the seed store: seeds sprout and mould, and the colony can collapse. Use distilled or purified water only, never tap water, rainwater or bottled mineral water.
Water the nest about once a week with the pipette provided. Pour very slowly, a drop at a time, through the watering hole. With harvesters, be extra careful: no more than 1 drop should leak into the nest.
Water only the brood corner, a little sooner in summer and later in winter. If the whole colony crowds into the damp corner, it is too dry: water it straight away. If seeds near the water start to sprout, you are watering too much.
Never water the outworld. Keep it dry, at about 50% humidity, like an average UK home.
Harvester ants must never have open water, because they can drown in it. Give them a watering test tube in the outworld, not a water dispenser.
Feeding Your Harvester Ants
🌾 Seeds are the main food. Give our 👉 harvester ant seed mix. Start with a small pinch and give more as the colony grows and collects it. A varied mix suits this choosy harvester best.
Always put the seeds on a piece of tin foil or in a 👉 small feeding dish in the outworld. Never put them straight on the substrate: damp seeds sprout, and sprouted seeds are harmful to the colony.
🥩 Once a week, for example every Monday, give a little 👉 Protein Jelly. The queen and brood need it to grow. Keep protein jelly in the fridge at all times.
🍯 Once a week on another day, for example every Thursday, offer our 👉 organic ant honey or 👉 Ant Nectar, which has even more carbohydrates than honey. Keepers find this species takes little sugar, but both are far better than sugar water.
As a rare treat, a rice-grain-sized piece of peeled grape or banana is fine too. Feed in the outworld only, and remove leftover jelly, honey and fruit after 2 days to stop mould.
Keep Mites Out of Your Colony
Blood-sucking mites are one of the biggest dangers for harvester ants, 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, check every colony twice a month, and check each colony again before it leaves us.
A home freezer won't kill all the mites in seeds, so never rely on it. We freeze our seeds below -60°C in a special freezer before they reach you.
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
A colony that likes to move house will test every gap, so escape-proofing 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 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; roll it gently instead.
Winter Care
In the wild, Veromessor andrei stops foraging in late autumn and starts again in spring. In captivity, give it a winter rest of 2 to 3 months, for example from December to February, at about 17 to 18°C. It does not need a cold hibernation.
Harvesters are sensitive to cold: 15°C is the absolute minimum, and 17°C or above is safe. Switch the heating off for the rest and let the room cool gradually. Never put ants in a fridge, shed or garage, and never move them from a warm room straight into a cold one.
If the room drops below 17°C, set the heater's thermostat to 17°C: it switches on at 16°C and off again at 17°C. We never give a queen a winter rest in her first year: keep her at her normal warmth.
The colony slows down in winter anyway, because its biological clock can't be tricked. 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.
Can I Release My Harvester Ants?
No. A colony raised indoors won't survive outside, and this species 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 Veromessor andrei good for beginners?
It is an intermediate species. Keepers find established colonies hardy and fast-growing, but the founding queen needs feeding, and in a UK home the nest needs gentle heating and very careful watering.
Can I buy Veromessor andrei in the UK?
Best Ants UK does not sell this species. It is a North American ant, and it may be illegal or impossible to import into the UK. We never encourage importing ants. Messor barbarus is a similar harvester that is kept and sold legally in the UK.
What do Veromessor andrei eat?
Seeds are their main food. Add Protein Jelly once a week and organic honey or Ant Nectar once a week on another day, although keepers find they take little sugar. Always feed in the outworld only.
How many workers before moving Veromessor andrei into a nest?
At least 10 workers, and 15 to 20 is even better. The same rule applies to a queen bought on her own: she stays in her test tube until she has raised enough workers.
What temperature do Veromessor andrei need?
Keep the nest at 24 to 28°C. Most UK homes are cooler than that, so use the Advanced Heating System Small set to 26°C under one quarter of a horizontal nest, opposite the watering area.
Do Veromessor andrei hibernate?
They need a winter rest of 2 to 3 months at about 17 to 18°C, not a cold hibernation. Never let them drop below 15°C. A queen in her first year stays warm through her first winter.
Do Veromessor andrei sting?
They are not known as a danger to people, but they defend their nest and can bite. As with every ant, never handle them.
Start Your Own Harvester Ant Colony
Print this guide and keep it next to your ant farm. In the UK, the easiest way to enjoy seed-gathering ants is a colony of Messor barbarus.
👉 Ready to start? Our A7 Plus ant farm kit has a pre-installed digital meter and a Nest + Outworld option, and it makes a superb home for harvester ants. 👉 Explore all our free ant care sheets.
