Myrmica rubra Care Guide: Keeping the Common Red Ant in the UK

Myrmica rubra is a familiar British ant, but it isn’t a red Lasius niger. It nests in damp ground, often has several queens in one colony, can spread across a network of nests, stings, and runs on a strongly seasonal cycle. For a keeper, the biggest practical difference is that a new queen is usually treated as semi-claustral, meaning she needs a way to feed, rather than being sealed in a tube until her first workers appear. This guide covers what the research says, where it runs out, and how to set up a colony sensibly.

Quick care summary

Care point Practical approach
Founding Semi-claustral husbandry: give an active queen safe access to food
First home Hydrated test tube attached to a small, secure feeding area
Carbohydrates Sugar water or another clean liquid sugar; sucrose is readily accepted
Protein Small pieces of pre-killed feeder insects, especially while larvae are growing
Nest moisture Reliably damp in one part of the nest, drier in another; never waterlogged
Active-season temperature Normal UK room temperature is a sensible start; no need for strong heating
Winter A real cool dormancy, roughly 5–10°C for three to four months, once the colony slows down
Queens Often several per wild colony; don’t add unfamiliar queens casually
Sting Yes. Set up feeding so your hands stay out of the nest

Natural habitat and British distribution

Myrmica rubra is native here and occurs across most of Europe and into temperate Asia. BWARS describes it as locally common in England and Wales, with scattered records in Scotland and Ireland. It likes sunny, warm, damp places such as meadows and river banks, and also turns up in gardens, parks, farmland and woodland edges. Nests go in the soil, under stones, in grass tussocks and in rotten wood. It’s rarely found on hot, dry, sparsely vegetated ground.

“Warm, damp habitat” can sound contradictory, but it isn’t. A sunny meadow can have a warm surface while the soil under the turf stays cooler and wetter. Surveys of nest sites in North America, where the species is invasive, found colonies preferring cool, moist soil. That’s worth remembering in captivity: temperature, the water held in your nest material, humidity inside a chamber and the reading on a room hygrometer are four different things.

Identifying Myrmica rubra

“Red ant” isn’t an identification. Several British Myrmica species are reddish. BWARS gives a few worker features to look at:

  • The antennal scapes are long and slender, with a gentle curve at the base.
  • The area between the two spines on the propodeum (the rear of the thorax) is smooth and shining.
  • The petiole node has an indistinct top that slopes smoothly down to the postpetiole.

The species most often confused with it is Myrmica ruginodis, which has ridges across the area between the spines and usually longer spines. Be wary of using spine length on its own, because it varies with body size. The sculpture between the spines is a much more reliable clue. M. scabrinodis and M. sabuleti need closer attention to the scape base and other details, and good close-up photos or a microscope will tell you far more than colour.

Queens look like larger, sturdier workers. Wing loss after mating is common but not proof of fertility, since a mated queen can keep her wings. Egg-laying alone doesn’t prove it either, because an unmated queen can lay unfertilised eggs. If you’re unsure of a British specimen, work through a proper key or our British Ant Identification Guide before settling on husbandry.

Queens, workers and colony structure

Workers vary in size, but there are no sharply separate major and minor castes like those in Messor or Camponotus, and no soldiers needing special care.

Wild colonies are usually polygyne, with several queens living together. BWARS gives an average of about 15 queens and a thousand or more workers, though those numbers vary and aren’t a captive target. They can also be polydomous, meaning one colony occupies several nest sites. Several entrances close together don’t necessarily mean several colonies.

Founding a new queen

British flights happen mainly in August and September. Accounts of the species’ life cycle describe newly mated queens overwintering, sometimes alone, sometimes with other queens, sometimes after entering an existing colony, and then looking for food in spring as breeding picks up. That’s the reason to treat a founder as semi-claustral. It’s reasonable, low-risk husbandry, but nobody has published an optimal captive feeding schedule, so there’s no research-backed number of feeds per week. Follow the queen’s appetite and her brood.

The simplest arrangement is a standard water-reservoir test tube joined to a small, secure feeding chamber. The tube stays as the dark, humid nest, and you offer a droplet of sugar and a tiny piece of pre-killed insect in the attached space without pulling the bung from a defensive queen’s home. Our Founding Pod is built around this idea. Whatever you use, check the lids, joints and tubing for escape routes yourself, and use a second layer of containment when servicing the colony.

Scale portions to a single queen and remove perishable leftovers before they go off. One ignored meal isn’t a problem, especially as autumn approaches. A queen collected after the usual flight period may do very little before winter.

Can you keep more than one queen?

Wild colonies manage it, but that doesn’t make it safe to mix queens yourself. Experimental work by Brian and others found that workers’ acceptance of a queen depends on previous colony association, whether familiar queens are present, how long the colony has been queenless and the time of year. Queens that came from the same colony could even become unacceptable to each other after being separated. Other researchers have documented alien queens being accepted under some conditions, so the picture is conditional, not a flat “always rejected”. That makes it unpredictable for a keeper.

Peaceful contact in the first few minutes proves nothing about long-term compatibility, and rejection can injure or kill workers and queens. Some retailers advise pooling three to five queens; the research gives no reliable basis for that. If you bought or collected a stable multi-queen colony whose queens coexist normally, there’s no welfare benefit in splitting them up. If one queen dies, don’t automatically add a replacement. The colony may carry on fine with the remaining queens.

Microgynes and the old name Myrmica microrubra

Some colonies contain unusually small queens, called microgynes, alongside the typical larger ones (macrogynes). They were once described as a separate species, M. microrubra. A 2006 study using morphology and several genetic markers concluded the two forms share a gene pool and merged the names. AntCat currently follows that, though it notes the status has changed back and forth over the years, and some authors still treat microrubra as a species.

Later work, by Schär and Nash in 2014, suggested microgynes can act as social parasites within the species, exploiting older host colonies. In their experiments, microgynes reproduced most in mixed nests that had lost their macrogyne queen. For keepers, the takeaway is simple: a microgyne isn’t just a small version of a normal founding queen, and it shouldn’t be introduced into a colony without a good research reason.

Feeding

In the wild, M. rubra takes honeydew and nectar and also hunts small animals. In a choice experiment with whole colonies, workers chose fructose over other simple sugars and sucrose over other double sugars, so ordinary sugar water is a sound carbohydrate source. That doesn’t pin down a single correct concentration for captivity.

Growing brood needs more than sugar. Older food-flow experiments showed workers passing prey-derived material to larvae, and larval feeding responds to prey availability. Commercial ant nectar works as a carbohydrate source if the formulation is suitable. “Protein jelly” is harder to judge because products vary a lot, and none of them should be assumed to replace whole insects. Seed mixes made for Messor aren’t a staple for this species.

Colony stage Carbohydrate Protein Water and management
Founding queen Tiny clean droplet while active Tiny piece of pre-killed fruit fly or similar Water-reservoir tube; small secure feeding area
Queen with first workers Small accessible feed Small pieces scaled to brood Keep the tube as the nest; make feeding low-disturbance
Growing colony Dependable access Fruit flies, mealworm pieces, suitable cricket or cockroach Separate drinking water in the outworld; remove waste
Established colony Feeder sized to consumption Varied captive-bred prey, adjusted to larvae Easy-to-service feeding area

Pre-killed captive-bred insects are a sensible default: they can’t hurt the ants, they’re easier to portion, and they avoid the pesticide, parasite and pathogen risks of wild-caught prey. Our general feeding guide takes the same cautious line.

Temperature and heating

Our Heating an Ant Colony guide covers thermostats and heat mats in detail.

M. rubra is a temperate ant with a lot of regional variation. For a normal UK home, the high teens to low twenties Celsius is a sensible starting range in the active season. That’s a husbandry suggestion, not a proven optimum. In a Danish laboratory study, colonies were held at a constant 26°C through the active season in water-reservoir tubes and developed normally, so slightly warmer conditions aren’t harmful in themselves. But warmth dries nests faster, and this species selects damp refuges.

If a room is unusually cold, warm only part of the setup and measure the surface rather than guessing. Don’t heat the whole nest or the water end of a test tube, and keep it out of direct sun, where a small enclosure can overheat quickly. The goal isn’t maximum activity. It’s a gradient the workers can move along.

Humidity, nest moisture and drinking water

Our What Is a Formicarium? guide explains how different nest materials handle hydration.

The evidence for damp nesting is much stronger than for any particular humidity percentage, so be sceptical of anyone quoting one magic number. Think in gradients: one part of the nest reliably damp for brood and adults, another drier. A water-reservoir test tube does this naturally. In a formicarium, gypsum, plaster or aerated concrete can spread water well when the design allows controlled hydration.

“Damp” doesn’t mean flooded. Heavy condensation, standing water and soggy waste areas shrink usable space and invite hygiene problems. Letting the whole nest dry out removes the refuge the species relies on. Once the colony has an outworld, offer drinking water separately, because damp gypsum isn’t a reliable substitute.

Founding setups and expanding the nest

A hydrated test tube is still one of the best homes for a queen and a young colony. The adjustment for M. rubra is feeding access: a small attached arena or pod lets the queen keep her compact tube while you put food away from her brood. A test-tube feeder insert can work where space is tight, though feeding directly inside the tube means getting closer to a defensive queen.

Don’t move a colony because it reaches 10, 15 or 20 workers. A clean, hydrated tube can stay an excellent nest while the colony is small. Move or expand when the setup becomes unsuitable: the reservoir is failing, feeding has become unsafe, crowding makes maintenance difficult, or the ants keep trying to use extra space. An oversized nest is harder to hydrate, makes waste harder to find and gives a small colony spare cavities to abandon food in. See Ant Outworlds Explained and Your First Workers for the next steps.

For a growing colony, look for a controllable damp zone, secure small gaps and connectors, and an outworld you can service without reaching among defensive workers. Gypsum and hybrid nests make moisture gradients easy to see. Natural soil gives wonderful digging but makes watching and intervening much harder. If the ants won’t move, connect the new nest and let differences in light, moisture and space persuade them rather than tipping them out.

For signs that a colony is ready to expand and ways to encourage a voluntary move, read When Should You Move Ants Into a Nest?.

Growth and normal behaviour

Growth is seasonal, not a smooth curve. Myrmica research distinguishes brood that develops quickly in the active season from slower brood whose larvae go dormant and finish developing after winter, though the details differ between regions. So don’t be alarmed by brood that stays much the same all winter, larvae being moved between chambers, queens spreading across a nest, foraging dropping off sharply in autumn, or entrances being narrowed with debris.

Winter dormancy

Our Ant Hibernation and Diapause Guide covers preparation in more detail.

Winter is where recent science most improves captive advice. A 2026 study by Willot and colleagues, which included M. rubra, worked with colonies collected in Denmark and kept warm and fed through the active season. The colonies went dormant on their own internal timetable, even though they were at 26°C. Dormancy was marked by stopped foraging, stopped egg-laying and larvae that had halted development. Warmth can delay dormancy but not prevent it, so keeping a colony warm all winter isn’t a way to skip it.

In that study, colonies were moved to 8°C for four months once dormant, then returned to warm conditions. Activity normally resumed within one to two weeks. That’s experimental context, not a deadline for your colony. The study was designed to test cold tolerance, not to find a pet-care temperature, and it used established colonies, not lone queens. Older work on Myrmica is consistent with this, and a northern colony shouldn’t be assumed to behave exactly like a southern one.

For UK keepers, a gradual cool period of roughly 5–10°C for three to four months is a defensible starting point. Let the colony’s slowdown lead, not the calendar. Before cooling, remove perishable food, check the water reservoir is secure and make sure nothing can flood or dry out while you’re not looking. Active workers in the study went into chill coma at about 0°C, so don’t chill a colony that’s still foraging. Keep it well above freezing: in the lab, half of cold-acclimated workers died after 24 hours at around −8.5°C, and that was the hardened best case. Garages and sheds can fall well below that.

During dormancy, hydration matters far more than food. When winter ends, warm the colony gradually, restart carbohydrates as activity returns and increase protein as larvae start growing again.

Newly mated queens overwinter naturally, so cooling a first-year queen is reasonable. But no study has tested lone first-year queens in test tubes, so treat the temperatures as husbandry judgement.

The sting and safe handling

Workers have a functional sting and defend a disturbed colony vigorously; BWARS notes they sting freely. A sting can cause a painful local reaction, and severe allergic reactions have been reported in susceptible people. That doesn’t make M. rubra interchangeable with medically important fire ants such as Solenopsis invicta. “European fire ant” is a common name used mainly in North America.

The practical answer is to build contact out of routine care. Use secure lids and connectors, feeding dishes you can lift out with long tweezers, and an outworld you can service without dismantling the nest. If workers escape, contain the room first rather than grabbing at ants with bare fingers. Move children and pets away, collect the ants with a secure method and fix the escape route before resuming normal care.

Common problems

The queen refuses food. One refused meal tells you little. Check whether autumn is approaching, whether the food is fresh and whether the reservoir is sound. Remove stale food rather than letting it mould.

The queen isn’t laying. Season, mating status, recent disturbance, food shortage or a natural pause could all be responsible. Wing loss can’t tell you whether she’s fertile.

Brood disappears. Workers and queens may eat brood under stress or shortage, but tiny brood can also be moved somewhere you can’t see it. Review food, moisture, temperature and disturbance before forcing a move.

Larvae stop growing in autumn. This is often normal. Dormant larvae are part of the species’ winter cycle.

Heavy condensation. Reduce excess hydration or heat while keeping a genuinely damp refuge. Don’t dry the whole nest out.

Workers attack a newly introduced queen. Separate her if you can do it safely. Don’t repeat the introduction on the theory that a polygynous species “should” accept her.

Is Myrmica rubra a good beginner ant?

It can be, but it isn’t the most forgiving first species. Compared with Lasius niger, you’ll think about feeding access earlier, keep nest moisture more dependable, manage a proper winter and work around a sting. Its multi-queen biology also invites experiments that beginners can easily mistake for routine care.

Lasius flavus needs seasonal care too, but its founding is conventionally claustral. Messor barbarus brings its own challenges with seed storage and moisture separation. Tropical Camponotus species remove the British winter question but need warmer conditions through the year. If you want a queen you can leave sealed in a tube until her first workers arrive, Lasius niger is usually easier. Compare these in our guides to Lasius niger, Lasius flavus, Messor barbarus and Camponotus nicobarensis.

Collection and release in the UK

M. rubra is native, so warnings written for releasing exotic ants don’t transfer one-to-one. Section 14 of the Wildlife and Countryside Act 1981 is aimed at releasing animals not ordinarily resident in Great Britain, or species covered by the Act’s schedules. Scotland has its own wording that makes release outside a species’ native range significant. Landowner permission still matters when collecting, and protected sites such as SSSIs can have extra rules. Check current guidance for your area before collecting or releasing.

Even for a native species, releasing a captive colony is a poor default. Its origin may be uncertain, and captive ants can carry feeder-organism pathogens or parasites that aren’t present at the release site. Rehoming through another responsible keeper is better.

Sources and further reading