Lasius flavus Care Guide: Keeping the Yellow Meadow Ant

Lasius flavus, the yellow meadow ant, is a small golden-yellow ant from Europe that spends almost its whole life underground. In the wild it builds the grassy mounds you see in old meadows and keeps root aphids for their honeydew, so you rarely see it in the open. In a formicarium it is one of the calmest and shyest species you can keep. A colony starts slowly, but with patience it grows into a large, busy nest. This guide explains how to keep it, based on our own experience with the species.

At a glance

• Origin: most of Europe, in grassland, meadows and gardens

• Difficulty: beginner

• Colony structure: queens often start together, and a colony can keep more than one queen

• Growth: slow at first, faster once there are more workers

• Colony size: large in the long run

• Temperature: room temperature, no heating needed

• Humidity: slightly moist, never completely dry

• Winter rest: required

• Diet: sugar water or sugar jelly and small insects, in small amounts

• Activity: low, they stay inside the nest most of the time

Appearance and size

Workers are small and golden yellow, with tiny eyes and very little dark pigment, which suits a life without daylight. They vary a little in size, roughly 2 to 4.5 mm, and the larger workers often have a slightly darker head. Queens are darker and clearly larger, roughly 7 to 9 mm. Because the workers are so small and pale, a colony is easy to tell apart from the black garden ant, Lasius niger.

Lasius flavus or Lasius umbratus?

Lasius umbratus is another yellow Lasius that lives underground, and the two are mixed up all the time. Look closely and you can tell them apart. Lasius umbratus workers are a bit larger and hairier, with clear standing hairs on the underside of the head and on the cheeks. The biggest difference is in the queens. A Lasius flavus queen starts a colony on her own or together with other queens. A Lasius umbratus queen cannot do that: she sneaks into a colony of another species, usually Lasius niger, kills its queen and lets the workers raise her first brood. Lasius umbratus also flies a little later, from mid August into late September, and its queens fly alone instead of in big swarms. So if you caught a yellow queen that never raises workers by herself, there is a good chance it is Lasius umbratus.

Colony structure

After the nuptial flight in late summer, several young queens often dig in together. This is called pleometrosis. A group of queens produces more eggs at the start, so the first workers arrive sooner and the colony gets going faster. In the wild, the queens of such a group sometimes fight once the first workers are there, until only one is left. Other colonies keep more than one queen for good. That is why we also offer Lasius flavus with two, three or five queens. Keep an eye on a multi-queen group once the first workers appear. If one queen is clearly attacked, it is best to separate her.

Founding a colony

Keep a founding queen, or a small group of queens, in a closed test tube until the first workers arrive. She does not need food in this phase, she lives on her own reserves. Put the tube in a dark, quiet place and check it as little as possible. Every look is stress for a shy species like this one. Our test tube guide explains how to set up the tube.

Growth

The first year is slow, so do not expect a busy colony right away. Once there are more workers, the colony speeds up, and in time it can become very large. How fast that goes depends on the number of queens, the temperature, the food and simply the colony itself. Two colonies kept side by side can develop completely differently, which is why we do not give timelines here.

Temperature and heating

Room temperature is fine for Lasius flavus. Heating is not needed. This is a species from cool European meadows, and it does well in a normal living room or bedroom as long as the setup is not in direct sunlight.

Winter rest

Winter rest is required. From late autumn to early spring, keep the colony somewhere cool, such as an unheated room or a shed that does not freeze. Feed little during this time, but always make sure there is water. In spring, bring the colony back to room temperature and the queen will start laying again. Skipping winter rest wears the colony out over the years.

Humidity and water

Keep the nest slightly moist. Lasius flavus likes damp soil and should never dry out completely. At the same time, too much water is not good either. Water drops on the walls, condensation or mould mean it is too wet. Workers crowding around the moist spot mean it is time to add a little water. Always provide clean drinking water as well.

Feeding

The most important rule is not to overfeed. A Lasius flavus colony eats little, and leftovers quickly start to mould in a small setup. Feed only when you see many workers outside the nest, because that is the sign they are hungry.

• Sugar: sugar water or sugar jelly. Be careful, because Lasius flavus drowns very easily in sugar water. Use a feeder or offer only a small drop.

• Insects: small pieces, such as fruit flies. Adjust the amount to the size of your colony and remove leftovers.

• Water: always available, also during winter rest.

Read more about feeding in What do ants eat?.

Housing

Because Lasius flavus is so shy, it hardly needs space. A small, dark setup works much better than a big nest with a large outworld. A big setup only makes it harder to see your ants and to keep things clean.

• Founding queen: a closed test tube until the first workers arrive.

• The first two years: a Mini Outworld V2 with one test tube is the best setup. A big nest or outworld is not needed.

• Larger colonies: move them to a Mesh Nest, or use the All-In-One Test Tube Outworld, which is perfect for this species.

Keep the nest part dark, for example with a cover, and only uncover it now and then to have a look.

Behaviour, biting and escapes

Lasius flavus is very calm. When you open or disturb the nest, the workers quickly close off their tunnels with soil and retreat. They can bite other insects and use formic acid, but they are far too small to bother people. The workers rarely leave the nest, so escapes are less common than with active species. They are very small though, so make sure your setup closes well and use an anti-escape barrier on the outworld. Our anti-escape guide shows how.

Is Lasius flavus right for you?

Lasius flavus is a great choice if you enjoy watching life inside the nest more than ants running around an outworld all day. It is easy to care for, harmless and needs only a small setup, which makes it suitable for beginners who have some patience. If you want a species that is active and visible all the time, choose something like Lasius niger instead. Ready to start? Have a look at our Lasius flavus colonies.