How to Care for Formica perpilosa | The Desert Formica Ant Guide
Updated: 3 days ago
Photo: Jason Eckberg, via iNaturalist, licensed under CC BY 4.0.
Formica perpilosa is a hairy, hard-working field ant from the dry south-west of North America. With its red head and body, black gaster and coat of fine white hairs, it is one of the most striking Formica ants you can watch.
The workers are fast, fearless foragers. This guide explains Formica perpilosa care step by step, from a queen in her test tube to a busy, well-fed colony.
Formica perpilosa is a North American ant, and Best Ants UK does not sell it. We don't encourage importing ants from abroad. This guide is for keepers where the species is native, and for anyone curious about this amazing desert ant.
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 Formica perpilosa care sheet (PDF) or open the Formica perpilosa care sheet page for the key facts at a glance.
Formica perpilosa at a Glance
Also known as: the Desert Formica
Origin: south-western USA and northern Mexico, north to Wyoming and Alberta
Keeping level: Intermediate
Queen: 7 to 8mm, orange-red head and body, black gaster
Workers: about 4 to 5mm, slightly different sizes, very hairy
Colony: one queen, up to a few thousand workers
Nest temperature: 24 to 28°C, best at around 26°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: very fast, so a PTFE barrier is a must
Meet the Desert Formica
In the wild, Formica perpilosa lives in deserts and dry country, but always close to a little moisture: river banks, the edges of dry streams, shady spots, irrigated land and even town gardens.
It nests in the soil, often around the roots of a bush or a grass clump, with a low mound or crater at the entrance. Its name means "very hairy", after the many white hairs on its body.
The workers collect honeydew from sap-sucking insects and scavenge dead insects from plants and the ground. They are active by day and very bold, often foraging when the ground is baking hot.
New queens leave on their mating flight in summer, mostly around July. Afterwards, a queen seals herself in a small chamber and raises her first workers alone, living on her own body reserves.
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. Moved earlier, the workers often abandon the queen in the bigger space, and 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.
Desert Formica brood grows fast when it is warm: often a little over a month from egg to worker. If the tube is cool, a heating cable at the cotton stopper end keeps it warm. Never put 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. 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.
These ants are timid and jumpy in the nest, so keep checks short and calm. Take colony photos no more than once a month.
The Best Ant Farm for Formica perpilosa
Desert Formica workers are fast and love to explore, so give them a well-made, escape-proof nest and a good-sized outworld.
👉 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: 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
This is a warmth-loving ant. Keep the nest at 24 to 28°C, best at around 26°C. Don't let it climb much above 29°C, even though the wild ants cope with hot ground outside.
Most UK homes are far cooler than that, especially from autumn to spring. 👉 The Advanced Heating System Small 4W holds the nest steady with its digital thermostat. Set it to 26°C.
The heat mat goes under one quarter of the nest only, on the side opposite the watering area. The ants can then move to the warm or cooler part as they like. 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
Even desert ants need a damp nest. 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. A watering test tube in the outworld gives the workers a safe drink.
Feeding Your Formica perpilosa Colony
Desert Formica are keen scavengers and big protein eaters. 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. Their larvae grow quickly, so give a little extra protein whenever you see larvae.
🍯 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. The workers often spray formic acid on food before they eat it, which is normal.
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, and live food bought from pet shops or online marketplaces.
Dried mealworms are also useless as ant food. 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
Desert Formica workers are fast 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
Formica perpilosa has a natural winter rest, and the colony slows down from late autumn whatever you do. Its biological clock can't be tricked. We never hibernate queens in their first year.
This desert Formica needs a shorter rest: a full hibernation of about 6 to 10 weeks at a steady 5 to 10°C, roughly December to February. 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. Formica perpilosa 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 Formica perpilosa good for beginners?
It is best for keepers with a little experience. The workers are fast, jumpy and quick to spray formic acid, and the colony needs steady warmth and plenty of protein while larvae are growing.
Can I buy Formica perpilosa in the UK?
Best Ants UK does not sell Formica perpilosa. It is a North American ant, and we don't encourage importing ants from abroad. UK keepers who love Formica can start with our native silky ant, Formica fusca.
How many workers before moving Formica perpilosa 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 and the colony can fail.
What temperature do Formica perpilosa need?
Keep the nest at 24 to 28°C, best at around 26°C, and never much above 29°C. Most UK homes need an Advanced Heating System under one quarter of the nest to reach that.
Do Formica perpilosa hibernate?
They have a natural winter rest. A full hibernation is only safe at a steady 5 to 10°C for 6 to 10 weeks 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 Formica perpilosa eat?
Protein Jelly or Cricket Mash for the queen and brood, and organic honey or Ant Nectar for energy. Feed twice a week in the outworld and give extra protein whenever larvae appear, because they grow fast.
Do Formica perpilosa sting or bite?
They have no sting. Workers bite and spray formic acid when disturbed, which can sting a little on sensitive skin. As with every ant, never handle them.
Ready for Your Own Formica Colony?
Every Formica colony grows into a lively, fast-moving show. When yours outgrows its first home, 👉 the A6 ant farm kit with meter gives a bigger 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.
