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Lasius flavus: 9 Facts About the Yellow Meadow Ant

8 hours ago
5 min read

Lasius flavus, the yellow meadow ant, lives in almost every old meadow, lawn and pasture in Europe. Still, most people have never knowingly seen one. It spends nearly its whole life underground, where it runs a small farm, looks after eggs that are not its own and slowly builds the grassy mounds you see in old fields. We checked the facts against recent research. Here are nine of them, followed by what they mean if you want to keep this species yourself.


1. It lives almost entirely underground

Lasius flavus is golden yellow, has very little dark pigment and tiny eyes. That is what a life without daylight does to an ant. Compared with the black garden ant, Lasius niger, it hardly ever comes to the surface. You usually only notice a colony when you lift a stone or a paving slab, or on the one summer evening when the winged ants come out.


Lasius flavus, the yellow meadow ant

2. It farms root aphids

Instead of hunting for food above ground, a Lasius flavus colony keeps root aphids on grass and plant roots inside its own nest chambers. The ants live mostly on the sweet honeydew these aphids produce, which is the main reason the workers rarely need to go outside. In winter, when the aphids produce less, the ants sometimes eat some of them as well. It really is a herd that gives milk and, now and then, meat.


3. It babysits aphid eggs through the winter

In 2025 Thomas Parmentier and Nicky Wybouw published a study showing how far this care goes. In winter they found the eggs of the root aphid Anoecia zirnitsi only inside Lasius flavus nest chambers. The workers recognise the eggs by a chemical signal on the surface, pick them up, pile them next to their own brood and groom them. With ants around, the eggs stayed almost free of mould, while eggs without ants were quickly overgrown. The ants also kept away a small rove beetle that eats the eggs. Six other ant species that were tested simply ignored them. The eggs can hatch without ants, so the help is all about getting the next generation of the herd safely through winter.


4. Queens often start a colony together

After the nuptial flight, several young queens often dig in together. This is called pleometrosis. More queens means more eggs at the start, so the first workers arrive sooner. 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 and can grow very large, sometimes spread over several connected nests. That is why we also offer Lasius flavus with two, three or five queens: a group of queens gets the colony going faster than a single queen. Do keep an eye on them once the first workers appear.


5. Its mounds can last for decades

The grassy mounds in old pastures are built by Lasius flavus. They grow slowly, year after year, and stay in use for a very long time. Near Oxford, the ant hills of Wytham Woods were mapped between 1955 and 1962 and again more than 60 years later. Most of them were still in exactly the same place. Some mounds are thought to be centuries old. A field full of them is a sign of grassland that has not been ploughed for a long time.


6. Those mounds are small nature reserves

A mound is drier and warmer than the ground around it, and the root aphids underneath favour some plants over others. Research from the University of Groningen found more red fescue growing on the mounds than around them. Other animals profit too. Chalkhill blue butterflies have a close relationship with the ants, which protect their caterpillars in return for a sugary secretion. Bare soil on the mounds gives seeds and insects a place to start. This is why the yellow meadow ant is called a keystone species of old grassland. You can read more about why ants are good for your garden in this post.


7. It is the green woodpecker’s favourite winter snack

Green woodpeckers are often seen sitting on ant hills, digging deep holes with their beak and long sticky tongue. In winter, when few other insects are around, Lasius flavus colonies are one of their most important food sources.


8. It flies in late summer

The winged queens and males leave the nest on warm days and evenings in July and August. The workers more or less push them out of the entrance. It is one of the few moments you see this species above ground in large numbers, and the flights are often a little later than those of Lasius niger.


9. It is shy and harmless to people

When a nest is opened, the workers quickly close off their tunnels with soil. Against other insects they can bite and use formic acid, but they are far too small to bother people. In a formicarium this makes them one of the calmest species you can keep. More surprising ant behaviour can be found in our 10 bizarre ant facts.


Bonus: it is often confused with 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.


Keeping Lasius flavus yourself

Everything above explains how this species behaves at home. Lasius flavus is very calm and shy and hardly needs space. A colony starts slowly in the first year, but once there are more workers it speeds up and can become large over time. You will notice we do not give exact numbers: every colony develops differently, so watch what your ants do instead.


  • Setup: keep a founding queen in a closed test tube until the first workers arrive (see our test tube guide). For the first two years a Mini Outworld V2 with one test tube is all you need. Larger colonies can move to a Mesh Nest or the All-In-One Test Tube Outworld.

  • Keep it small and dark, and disturb the colony as little as possible.

  • Room temperature is fine. Extra heating is not needed.

  • Keep the nest slightly moist, as they like damp soil, and never let it dry out completely.

  • Do not overfeed. Feed when you see many workers outside the nest, which is the sign they are hungry.

  • Sugar water or sugar jelly works well, but Lasius flavus drowns very easily, so use a feeder or offer only a small drop. Add small pieces of insects such as fruit flies, and always provide clean water.

  • Winter rest is required. From late autumn to early spring keep the colony somewhere cool that does not freeze, feed little and always give water.


Want to watch an underground farm up close? Have a look at our Lasius flavus colonies.


Sources

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