Black garden ant

Lasius niger

Where it comes from

Range

Across Europe and much of the Palaearctic

Size

Workers 3–5 mm, queen 8–9 mm

Queens

One queen; several may found together and all but one are killed

Keeping them

Diet

Sugar water and small insects

Founding

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

Brood development

Egg to worker in roughly 6–8 weeks at 24 °C

Nest

Ytong, plaster or acrylic with one damp end and one dry end

Wintering

5–10 °C — a cellar, an unheated room or the salad drawer

The classic first colony: forgiving about humidity, quick to grow and happy to eat almost anything you offer.

Starting a colony

Lasius niger queens fly in high summer, usually in July or August on a warm, humid afternoon, often after rain. A queen that has shed her wings has mated and is looking for a place to dig in, and that is the moment to collect her.

House her in a test tube: water at the back, held in place by a plug of cotton wool, the queen in the dry front half, and a loose plug of cotton at the opening so air gets in. Cover the tube against light, keep it at 21–25 °C and leave it alone. She is fully claustral: she raises her first workers on her own reserves and needs no food until they arrive. At 24 °C that takes roughly 6–8 weeks, longer when it is cooler. A queen collected late in the summer sometimes waits: she goes into the winter with eggs or larvae and her first workers appear in spring. That is normal, not a colony that has stalled.

Keep one queen per tube. Lasius niger queens sometimes found a nest together, but once the first workers are out they fight until one is left, and it is not always the one you would have kept.

Feeding

Once the first workers are out, offer food in small amounts: a drop of sugar water or diluted honey, and some protein — a fruit fly, a piece of cricket or a cut mealworm. In the wild this species farms aphids for their honeydew, which is why sugar is its staple. Protein is what the larvae grow on, so how much the colony wants rises and falls with the amount of brood. A young colony needs very little; a feeding or two a week is plenty. Remove uneaten insects after a day, because in a small, damp setup they go mouldy fast.

The nest

A young colony is best off in its test tube, and usually stays there through its first year. Moving it to a large nest too soon is the classic mistake: a handful of workers cannot keep that much space clean or damp enough, and food carried into empty chambers goes mouldy. Move them when the tube gets crowded or the water runs low. Connect the old tube to the new home and let the workers carry the brood across themselves.

After that Lasius niger is not fussy. Ytong, plaster and acrylic all work, as long as one end is damp and the other dry, so the workers can choose. They are only 3–5 mm long and squeeze through small gaps, so give the outworld a barrier along the top of its walls: PTFE (Fluon) or a thin film of paraffin oil. Expect slow growth in the first year, from a handful to a few dozen workers by the first winter. It picks up from the second year, and a colony reaches several thousand workers after a few years.

Hibernation

Lasius niger needs a winter rest from November to February at 5–10 °C: a cellar, an unheated room or the salad drawer of a fridge. The colony usually tells you when it is time. In autumn the workers eat less, the brood stops growing and the ants cluster together. Lower the temperature over a couple of weeks rather than in one go, and stop offering insects. Check the water every few weeks, because a test tube that dries out over the winter kills the colony. In spring, warm them up just as gradually. A founding queen with her first few workers hibernates too.

Common mistakes

• Checking on a founding queen every day. Every look brings light and vibration, and a stressed queen can eat her own eggs.
• Feeding a queen before her first workers arrive. She does not need it, and the food goes mouldy.
• Moving a small colony into a big nest.
• Leaving uneaten insects in the setup.
• Skipping the winter, or letting the tube dry out during it.

Questions keepers ask

How long until the first workers? About 6–8 weeks at 24 °C. It takes longer when cooler, and a queen collected late in the summer often waits until spring.

Does it need a heat mat? No. Ordinary room temperature is enough for this species. Keep the setup out of direct sun, which heats a small tube far more than you would expect.

How long does a queen live? A long time. A Lasius niger queen kept in a laboratory lived for almost 29 years, which makes this one of the longest-lived insects known.

Can I keep two queens together? Not for long. Queens may found a nest together, but once there are workers all but one are killed.

Check it yourself

• AntWiki: Lasius niger

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

• 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 %

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• Formica fusca Silky field ant

  Europe and northern Asia, in open woodland and clearings

  22–26 °C 50–70 %

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• Temnothorax nylanderi Acorn ant

  Western and central Europe, in woodland leaf litter

  20–24 °C 50–60 %

  Beginner

All 21 species in the guide