Pavement ant

Tetramorium caespitum

Where it comes from

Range

Europe, in paving, gravel and any warm dry gap

Size

Workers 2–4 mm, queen 6–8 mm

Queens

One queen

Keeping them

Diet

Insects, seeds and sugar water

Founding

Fully claustral — the queen needs no food until her first workers

Brood development

Egg to worker in roughly 6–8 weeks at 26 °C

Nest

Mostly dry, warm, and sealed better than you think you need

Wintering

5–10 °C

Tiny, tough and fast-growing. Seal the outworld properly: workers fit through gaps you would not think of as gaps.

Starting a colony

Tetramorium caespitum is the ant that nests under paving stones and in gravel, and its queens fly in early summer, sometimes in large numbers straight out of the pavement. A queen is 6–8 mm long, dark and stocky, and once she has shed her wings she has mated.

House her in a test tube: water at the back behind a plug of cotton wool, the queen in the dry front half, and a loose plug at the opening. She is fully claustral and lives on her own reserves until her first workers arrive. Keep the tube covered, at 24–28 °C if you can, and leave it alone. At 26 °C, egg to worker takes roughly 6–8 weeks. Once the first workers are out, growth is quick: this is one of the fastest-growing species in the guide.

Feeding

Tetramorium eats a bit of everything: insects, seeds and sugar water. Give insects whenever there is brood — fruit flies, crickets, cut mealworms — a few small seeds such as grass seed, chia or poppy, and sugar water or diluted honey. A colony that grows this fast needs a lot of protein, and a hungry colony is easy to recognise: the workers swarm anything you put in. Remove insect remains after a day.

The nest

Keep it mostly dry and warm, with a small damp area. Ytong, plaster and acrylic all work, and a heat mat under one end helps in a cool room. The real challenge is sealing the setup. Workers are 2–4 mm long and get out around tubing, under a lid, or through ventilation holes that are fine for larger species. Use fine mesh, check every seam, and put a barrier — PTFE (Fluon) or a thin film of paraffin oil — along the top of the outworld.

Plan for growth. A colony can reach tens of thousands of workers, and it will outgrow a first nest within a year or two. Keep the young colony in its test tube until it is crowded, then connect it to a larger nest and let the workers move themselves.

Hibernation

Tetramorium caespitum needs a winter rest from November to February at 5–10 °C: a cellar, an unheated room or a fridge. Lower the temperature over a couple of weeks and stop offering insects. Check the water every few weeks, because a nest that dries out over the winter kills the colony, and warm them up gradually in spring.

Common mistakes

• Gaps in the setup. Small ants find every one.
• Too little protein for a colony that grows this fast.
• A nest that is damp throughout.
• No plan for where the colony goes when it outgrows its nest.
• Skipping the winter rest.

Questions keepers ask

Why do they fight on the pavement in spring? Neighbouring colonies meet at the border between their territories and fight it out in large crowds. It looks dramatic, but most of it is pushing and grappling, and far fewer ants die than you would expect.

Is it really Tetramorium caespitum? Possibly not. In 2017 what used to be called Tetramorium caespitum was split into several species that look almost identical, and the common pavement ant of towns and cities is often Tetramorium immigrans. You cannot tell them apart without a microscope, and the care is the same.

How long until the first workers? About 6–8 weeks at 26 °C, and longer when it is cooler.

Is it a good first species? Yes. It is tough, grows quickly and eats almost anything. Get the setup escape-proof before the colony grows, not after.

Check it yourself

• AntWiki: Tetramorium caespitum

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

• Formica fusca Silky field ant

  Europe and northern Asia, in open woodland and clearings

  22–26 °C 50–70 %

  Beginner
• Lasius emarginatus Two-coloured garden ant

  Central and southern Europe, the Caucasus and Asia Minor

  22–26 °C 50–65 %

  Beginner
• Lasius flavus Yellow meadow ant

  Europe and across the Palaearctic, in grassland and meadows

  20–24 °C 60–80 %

  Beginner
• Lasius niger Black garden ant

  Across Europe and much of the Palaearctic

  21–25 °C 50–70 %

  Beginner

All 21 species in the guide