Lasius flavus (yellow meadow ant)

Introduction to Lasius flavus

Lasius flavus, the yellow meadow ant, spends most of its time underground. They prefer not to move out in the open visible to the sun and predators. Instead, they are very well adapted to life beneath the surface. In their small tunnels, they hunt for insects. They are very shy and friendly and tend to keep underground aphids.

Appearance of Lasius flavus

Worker: Length 2-4,5 mm. Color varies from brown-yellow to bright yellow. Legs and body are relatively hairy with hairs aligning with the shape of the body. The head is more sparsely haired with tiny eyes. The hairs are long and stand up on the top of the abdomen and middle body segment (this separates the species from the very much alike species of Lasius bicornis. The species do not have these hairs on the first part of the abdomen, postpetiole). The upper part of the middle segment is wider than the lower parts. They have a small scent of citrus which can be picked up by humans. The rare Lasius carniolicus is one of the Lasius species with the strongest citrus scent. Workers of Lasius flavus can vary in size depending on climate. In the northern parts of their distribution area (for example Scandinavia) the workers have a much more diverse size difference in-between one another. In the southern parts the size of the flavus workers are more the same.

Queen: Length 7-9 mm. In comparison with the worker yellow of her daughters, the queen is more brown (varies between light and dark brown, but her underbody is always lighter). Same hair as the workers. The head is clearly thinner than the rest of the forepart of the body. The eyes are haired with many short hairs.

Males: Length 3-4 mm. Darker than the queen, more a black and brown or dark brown color. Lacks hairs on the long inner segment of the antennas. Just as the queen the head is thinner than the forepart of the body.

A typical Lasius flavus nest. Discretely situated in the grass. Photo: Antkeepers

Distribution

Found throughout the world. From the northern parts of Africa in the south to the northern parts of Europe. Also found across Asia. It is one of Europe’s most common ant species.

Nuptial flights

The mating of Lasius flavus often take place in late July or during the first half of August. The workers help the young queens and males to get out of the nest and fly away. The queens often mate with more than one male.

Lasius flavus habitat and nests

Can nest together with Lasius niger, Myrmica sp. and Formica fusca. Often nests in the borderlands of woods and open landscapes. Also likes to settle in groves and meadows. Larger nests often take the shape of domes covered in grass. Lasius flávus are experts in underground tunnel systems. A nest can have as many as 10.000 workers, but colonies up to 100.000 workers can be found in very favorable nesting conditions. It seems as though Lasius flavus likes locations that are not affected by shadow. The mostly nest in south or west slopes. If not, they try to shape their nest to lean towards this direction to get the maximum amount of heat from the sun. Their nest entrances are often small and hard to spot and are sometimes completely covered up.

Lifespan

The life expectancy of the workers is unknown. Queens in laboratories have been studied and are said to live for 18 years on average, with a record of 22,5 years.

Castes

The caste system of the Lasius flavus species is strongly built on the worker age. The youngest ones stay behind in the nest to care for the brood and queen. Meanwhile their older sisters take care of the nest and forage for food and supplies.

Lasius flavus – from egg to ant

The process from egg to ant is pretty much the same as in Lasius niger. Approximately 8-9 weeks for a fully developed worker to appear. Lasius flavus larvae spins cocoons.

Behaviour

Lasius flavus spends most of their time in the round. They are shy and seldom move out in the open or visibly during the day. They are instead well adapted to a life beneath the surface and therefore have very small eyes. In their nest tunnels they hunt for prey in the form of small insects, but they also keep aphids that feed on the root systems. The aphids are valuable to the ants and provide a sweet substance that the ants drink. They are well taken care of and protected by the ants in exchange. When one of the aphid’s feeding roots go bad the ants simply move the “herd” to a new location within the nest.

Lasius flavus is a fully claustral species, able to form new societies with a single queen. But it is very common for the queens to huddle up together in what’s called pleometrosis, multiple founding queens. After some time the queens fight each other to the death and normally there’s only one left standing to reign the colony. If colonies have more than one queen they often live separated from each other in the nest.

Parasites

The larvae of the polyommatini butterfly (Lysandra coridon amongst others) use the nests and workers of Lasius flavus to their advantage. The workers gently cares for the larvae and cover them with dirt. The reason for this is that the larvae produces a sweet nectar that the ants drink (very much like their relationship with the aphids).

Captivity

Lasius flavus is an easy species to care for at home. They quickly increase their numbers, especially with several queens present. They can be kept without or with a very small outworld because of their love for the underground. Compared with Lasius niger they seldom try to climb out of the formicarium. Remember, they are very shy!