HYMENOPTERA > APOCRITA | Aculeata > Formicidae > Formicinae > Lasiini

A small to medium-sized, dark-coloured species, with workers that average around 4-5mm and queens that may grow to 8-9mm. Although commonly known as a black ant, brownish-black would be a more accurate description. The colour though is rather dependant on the light, because they certainly look much paler than they actually are when photographed in bright sunshine. The head and gaster are consistently darker with the mesonoma often appearing a little lighter. Distinguishing features that may be visible in good photos include a scattering of erect hairs on the first antennal segment (scape) and also on the tibiae of all legs, and distinct pubescence on the clypeus.          

Lasius niger prefers fairly dry, sunny sites where its nests are formed of a small mound of soil. In natural habitats it would most likely be found on heathland, but is just as likely to be present in gardens. It is also common in more urban areas and will readily nest under stones, paving slabs or cracks in pavements where all it needs is a small entrance hole. It is the only indigenous British species known to enter houses.

It could be confused with the Humid Ant, Lasius platythorax, but the habitat should confirm as that species is far more likely to be found in wetland areas or damp woodland.

The alates, winged males and potential future queens, are the familiar flying ants that are sometimes seen in large numbers on certain warm summer afternoons during late July and August.

Workers can be aggressive and forage boldly, scavenging and predating various small invertebrates. They also tend aphids, milking them for honeydew. It’s when outdoor food sources are scarce that they are most likely to enter houses, especially if sweet substances are left out. That’s when they can become a nuisance, but it’s usually only for a short time early in the season, which is typically April to September.