Lasius niger Care Guide: Keeping the Black Garden Ant

Lasius niger, the black garden ant, is one of the most common ants in Europe. You find it in almost every garden, along pavements and under paving stones. Because it is so common, people often underestimate it. Yet it is one of the most fun species to keep and a perfect first ant. In this guide you will read how it lives in the wild and how to care for a colony at home.

At a glance

• Origin: Europe and parts of western Asia

• Difficulty: beginner

• Colony structure: one queen per colony

• Growth: fast for a European species, especially with some warmth

• Colony size: large, mature colonies can reach thousands of workers

• Temperature: room temperature is fine, a little heat speeds things up

• Humidity: fairly moist, hydrate now and then but not too much

• Winter rest: required

• Diet: mostly sugar, plus small insects for the brood

• Activity: high, you see them out and about a lot

Where do they live?

Lasius niger is native to Europe and parts of western Asia. It nests almost anywhere: in walls, under pavements, in tree stumps, in meadows and on heathland. It adapts well to its surroundings and defends its territory fiercely against other colonies. Older books say the species lives across the whole northern hemisphere, but most of the North American and East Asian ants that were once called Lasius niger have since turned out to be separate species.

True farmers

Lasius cf. niger tending aphids. Photo: Michal Kukla.

Lasius niger loves sugar, and much of it comes from aphids. Aphids suck sap from plants and give off a sweet liquid called honeydew. The ants protect the aphids from predators and "milk" them by tapping them with their antennae. They also drink flower nectar and collect dead insects, but the bulk of their diet is sugar. Some colonies even take aphid eggs into the nest over winter, so their herd is ready again in spring.

How to recognise them

A Lasius niger worker. Photo: Gino Brignoli, CC0, via iNaturalist.

Lasius niger is brownish black and fairly small. Workers are roughly 3 to 5 mm long, and the queen is clearly bigger, roughly 8 to 9 mm. A few species look very similar. Lasius platythorax and species from the Lasius grandis group have fewer hairs on the clypeus, and Lasius cinereus has a lighter thorax. For most people that difference is hard to see without a magnifying glass, but the habitat helps: Lasius platythorax prefers damp woodland, while Lasius niger likes open, sunny and urban places.

The nuptial flight

Lasius niger usually flies in summer, often after a rain shower on a warm, humid day. Then huge numbers of queens and males take off at the same time all over Europe, so many that the swarms have shown up on weather radar over England. That is necessary too, because only a tiny share of the queens manage to start a colony. If you want to catch a queen yourself, take a walk after such a summer shower and you will often find young queens looking for a place to dig in.

Swarms of flying ants on Met Office radar over southern England (Sky News).

Founding a colony

A Lasius niger queen. Photo: Virn Stothers, CC BY 4.0, via iNaturalist.

A young queen raises her first workers entirely on her own reserves, so she does not need food in this phase. Keep her in a closed test tube with water on one side and a cotton plug, in a dark and quiet place, and check on her as little as possible. Our test tube guide shows how to set one up. In the wild, several queens sometimes start together, but a Lasius niger colony ends up with just one queen. Keep one queen per colony.

Growth

Lasius niger is one of the faster growing European species. Once the first workers are there, start feeding small amounts and the colony will pick up speed. How fast it grows depends on warmth, food and the colony itself, so two colonies side by side can develop very differently. That is why we do not give timelines here. With patience a colony can grow into thousands of workers.

A young Lasius niger colony in a test tube.

Temperature and heating

Lasius niger is not demanding. Room temperature is fine. If you heat one side of the nest, the brood develops faster and the colony grows quicker, but it is not necessary. Keep in mind that the setting on a heat mat is not the temperature inside the nest. Heat only one side so the ants can choose, and watch where they put their brood.

Winter rest

Lasius niger needs a winter rest. In autumn, move the colony to a cool place, such as a basement, garage or the fridge (if your housemates are fine with that). Feed them well before winter, then they need almost nothing during the rest period. You can offer a little food now and then, and always make sure there is water. In spring, bring them back to room temperature and the colony starts up again.

Humidity and water

Keep the nest fairly moist: hydrate now and then, but not too much. Look at where the brood is lying, that tells you whether the humidity is right. Brood piled up near the moist part means it could use more water, while condensation, water drops or mould mean it is too wet. Always provide clean drinking water as well.

Feeding

Lasius niger is easy to feed, because it eats almost anything. Sugar is the main food, so give sugar water, honey water or sugar jelly. Add small insects, such as fruit flies, for the brood. Adjust the amount to the size of your colony and remove leftovers before they go mouldy. Be careful with open sugar water for small colonies, as workers can drown in it. Read more in What do ants eat?.

Nest and outworld

Lasius niger fits in almost any nest, such as Mesh Nests, Ytong, acrylic or plaster. We do not recommend wooden nests. Because the workers are small, the outworld does not have to be big. A normal size is enough for a few years, and when the colony really grows you can move to a larger outworld.

Lasius niger colony inside a small Esthetic Ants Mesh Nest.

Behaviour, biting and escapes

Lasius niger is active and you will often see workers out in the outworld, which makes it a great species to watch. Workers can bite and spray a little formic acid, but they are far too small to hurt people. They are good climbers and can squeeze through small gaps, so make sure your setup closes well and use an anti-escape barrier on the outworld. Our anti-escape guide explains how. One more fun fact: Lasius niger queens can live for a very long time. In captivity a queen once reached almost 29 years, one of the oldest insects ever recorded. Read more in How old can an ant get?.

Is Lasius niger right for you?

Lasius niger may look ordinary, but it shows a lot of fun behaviour and is very easy to care for. Whether you are just starting or have kept ants for years, there is always something to see. Have a look at our Lasius niger colonies or read which ant species to choose for your first ant farm. Below you can watch a video about Lasius niger.

Keeping ants in the United States?

True Lasius niger is not established in the United States. On our US store, Esthetic Ants USA, you will find a care guide for its native look-alike, the cornfield ant (Lasius neoniger). For other species that are easy to find in America, see the best beginner ant species for your part of the USA.

Sources

• AntWiki. Lasius niger.

• Sky News, 2021. Giant swarm of flying ants spotted from space over UK.

• Wikipedia. Lasius niger.

Photos: Lasius niger queen © Virn Stothers, CC BY 4.0, via iNaturalist. Lasius niger worker by Gino Brignoli, CC0, via iNaturalist. Aphid photo by Michal Kukla.