Two-coloured garden ant

Lasius emarginatus

Where it comes from

Range

Central and southern Europe, the Caucasus and Asia Minor

Size

Workers 3–5.5 mm, queen 8–10 mm

Queens

One queen, though several often found together and only one remains

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 6–9 weeks at 24 °C

Nest

Ytong, plaster or acrylic — a rock dweller, so drier than Lasius niger

Wintering

5–10 °C

A red-brown thorax between a dark head and gaster makes it the easiest Lasius to recognise. Climbs well, so mind the lid.

Starting a colony

Lasius emarginatus queens fly in summer, usually in July or August, on warm afternoons. A queen that has dropped her wings has mated and is looking for a crack to crawl into. In towns she often picks a gap in an old wall or between paving stones, because that is where this species lives: it is a rock dweller, and to an ant an old wall is rock.

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 so air gets in. Cover it, keep it at 22–26 °C and leave it alone. She is fully claustral and raises her first workers on her own reserves, so she needs no food until they arrive. At 24 °C, egg to worker takes roughly 6–9 weeks. A queen caught late in the summer may go into the winter with eggs or small larvae and finish raising them in spring.

Several queens often start a nest together. Once the first workers are out they fight until one is left, so keep one queen per tube.

Feeding

Like its relative Lasius niger, this species farms aphids for their honeydew, so sugar is its staple: sugar water or diluted honey. Protein is for the brood: a fruit fly, a piece of cricket or a cut mealworm when there are larvae to feed. Workers find food quickly and are bolder about it than Lasius niger, which makes feeding time worth watching. Give small portions and remove uneaten insects after a day.

The nest

In the wild Lasius emarginatus nests in rock crevices, under stones and in walls, so it wants a nest that is drier than most Lasius would like. Ytong, plaster and acrylic all work. Keep one end damp and let the rest dry out, and the workers will settle where it suits them. A young colony is best off in its test tube through its first year. Move it when the tube gets crowded, by connecting the tube to the new nest and letting the workers carry the brood across.

This is a climber. Workers run up the walls of an outworld without effort, so the barrier along the top — PTFE (Fluon) or a thin film of paraffin oil — and a lid that really closes matter more here than with most beginner species. Growth is much like Lasius niger: slow in the first year, a few dozen workers by the first winter, and a lot faster from the second year on.

Hibernation

Lasius emarginatus needs a winter rest from November to March at 5–10 °C: a cellar, an unheated room or a fridge. In autumn the colony slows down by itself. The workers eat less, the brood stops growing and the ants cluster together. Lower the temperature over a couple of weeks, stop offering insects, and 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.

Common mistakes

• A lid that does not close. This species climbs, and a small colony that has escaped is hard to get back.
• A nest that is damp all the way through. It comes from walls and rock crevices and wants a dry area to sit in.
• Opening the tube to look for eggs. Every look brings light and vibration to a queen who needs neither.
• Moving a handful of workers into a large nest.
• Skipping the winter rest.

Questions keepers ask

How do I tell it from Lasius niger? By colour. Lasius niger is dark brown to black all over. In Lasius emarginatus the middle section, between the head and the gaster, is red-brown, and you can see it without a magnifier.

How long until the first workers? About 6–9 weeks at 24 °C. It takes longer when cooler, and a queen caught late in the season may wait until spring.

Does it need a heat mat? Not usually. It likes things a little warmer than Lasius niger does, so a warm room or a heat source under one end of the nest speeds up the brood, but ordinary room temperature works. Keep the setup out of direct sun.

Is it a good first species? Yes. It is as forgiving as Lasius niger about food and temperature. The one thing to get right from the start is a setup it cannot climb out of.

Check it yourself

• AntWiki: Lasius emarginatus

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 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
• Formica fusca Silky field ant

  Europe and northern Asia, in open woodland and clearings

  22–26 °C 50–70 %

  Beginner
• Temnothorax nylanderi Acorn ant

  Western and central Europe, in woodland leaf litter

  20–24 °C 50–60 %

  Beginner

All 21 species in the guide