Over the last week or two, I have spent a long while watching ants running along a local metal fence and noting that the ants are all quite slender when travelling away from the nest and return with swollen abdomens. Last year, I identified these as Jet ants but I didn't follow the full story. To quote: The Jet Ant, Lasius fuliginosus, is a semi-social parasite of a semi-social parasite; that is, the species establishes its colonies in Lasius umbratus nests which are in turn founded in colonies of the Lasius niger/flavus species. The workers often forage on trails leading some distance from the nest to trees where they tend Homoptera for honeydew. Most of their diet appears to come from this source and they rarely seem to take insect prey; however, dead aphids are occasionally seen being carried back in workers' mandibles and they will take dead insects if offered. The nests themselves are made from a type of carton (wood fragments cemented together with saliva), usually in the hollow of a partially rotted tree, log or stump, or within a hedge bank or wall.
