European fire ant
Myrmica rubra
Where it comes from
- Range
- Europe and northern Asia; introduced in North America
- Size
- Workers 4–6 mm, queen 5–7 mm
- Queens
- Usually several queens sharing one nest
Keeping them
- Diet
- Insects, some sugar water
- Founding
- Semi-claustral — the queen forages and must be fed while founding
- Brood development
- Egg to worker in roughly 7–9 weeks at 23 °C
- Nest
- Damp nest — this is one of the species that really wants it wet
- Wintering
- 5–10 °C
Stings, and means it. Usually polygynous, so several queens sharing one nest is normal rather than a problem.
Starting a colony
Myrmica rubra queens fly in late summer, usually in August and September. Unlike most species in this guide, the queen is semi-claustral: she does not live off her own reserves while she raises her first workers, but goes out to find food. In captivity that means you feed her.
Set her up in a test tube with water at the back behind a plug of cotton wool, the queen in the dry front half, and the opening connected to a small outworld, or left plugged and opened briefly to feed. Every few days, offer a fruit fly or a small piece of insect and a tiny drop of sugar water or honey on a piece of foil. Remove leftovers before they go mouldy. At 23 °C, egg to worker takes roughly 7–9 weeks. A queen caught in late summer usually overwinters with larvae, and her first workers appear in spring.
Mature colonies usually have several queens, and queens from the same flight can often be kept together. There is no need to separate queens that are getting along.
Feeding
Myrmica rubra is mainly a hunter and scavenger. Insects are its main food: fruit flies, crickets, mealworms, and live prey if you want to watch it hunt. Sugar water or diluted honey is welcome but plays a smaller part than for a Lasius or Camponotus colony. Feed small portions and remove what is left after a day.
The nest
Few species in this guide want it as wet as this one. Keep most of the nest damp, with humidity in the 60–80 % range, and only a small dry area. Plaster, Ytong and soil-filled nests all work. Room temperature, 20–25 °C, is enough, and no heat mat is needed.
Workers are 4–6 mm long and climb, so give the outworld a barrier along the top and a lid. A colony grows to a few thousand workers. And it stings: use forceps or a brush for anything you need to do inside the setup, never your fingers.
Hibernation
Myrmica rubra needs a winter rest from November to February at 5–10 °C: a cellar, an unheated room or a fridge. Larvae that are not finished by autumn simply stop growing and pick up again in spring, so a colony full of larvae going into the winter is normal. Lower the temperature over a couple of weeks, stop offering insects, and keep the nest damp through the winter.
Common mistakes
- Leaving a founding queen without food, as you would a claustral queen.
- A nest that is too dry.
- Handling the ants with your fingers.
- Separating queens that are getting along.
- Skipping the winter rest.
Questions keepers ask
Does it sting? Yes. The sting burns like a nettle for a while. It is not dangerous unless you are allergic to insect stings, but it is a good reason to keep your hands out of the setup.
Why is it called the European fire ant? The name comes from North America, where it was introduced and has become a pest. It is not a true fire ant, and it is not on the EU list of banned species. If you live in North America, check the local rules before keeping it.
How long until the first workers? About 7–9 weeks at 23 °C, and for a queen caught in late summer, usually not until spring.
Is there anything special about its nests in the wild? The caterpillars of some large blue butterflies are carried into Myrmica nests by the workers and raised there as if they were ant brood. The dusky large blue depends mostly on Myrmica rubra. For a closely related species that likes it even cooler, see Myrmica ruginodis.
Check it yourself
General guidance from the usual beginner references — treat it as a starting point, not as a rule your colony has agreed to.
Start a colony with this species
Similar species
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Myrmica ruginodis
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20–24 °C 60–80 %Intermediate -
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