This species has a wide distribution in Europe and Asia, from Portugal and Ireland in the west, Finland in the north to Italy in the south, and eastwards to Korea and Japan.

[3][4] Workers of Lasius fuliginosus have a black shiny colour, a relatively large head, broadly cordate, with a distinct posterior emargination and rounded occipital lobes.

[5] The species is associated with the nitidulid beetle Amphotis marginata, called the "highwayman" of the local ant world.

[5] The species builds a "cardboard" nest in old hollow trees, using "board" – a mixture of chewed wood with saliva similar to termites.

[6] Like other black ants they tend populations of aphids for their honeydew, and can often be seen travelling in both directions, following scent-trails for long distances to their source of food, which is often a tree.

In Lasius niger, the smaller but much more common (in the UK) black ant species, a queen founds its own nest by laying eggs and then feeding the new larvae with a fluid produced by breaking down its own muscles; a process that leaves her very weak as she cannot tend the larvae and forage for food at the same time.