Jet Ant - Lasius fuliginosus

Alternative names
Jet Black Ant

This ant is shiny jet black in colour with a heart-shaped head. Workers are about 4 to 6 mm long, females are larger and small males reach a length of 4.5 to 5 mm.

Identification difficulty
Recording advice

Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.


See Life History

When to see it

Usually recorded in summer.

Life History

It is a semi-social parasite of a semi-social parasite; that is, the species establishes its colonies in those of the Lasius umbratus group which are in turn founded in colonies of the Lasius niger/flavus species complexes. The chances of success for a founding queen under these circumstances may well result in the highly localised distribution of colonies seen in the field. Occasionally, nests are found with the black L. fuliginosus and yellow or brown host workers still intermixed. 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.

UK Status

This species is not rare in southern England and Wales but always tends to be locally uncommon, with often only a few isolated nests known to recorders in any one locality. There appears to be contraction in the range of L. fuliginosus in northern and central England.

VC55 Status

Rare or under recorded in Leicestershire and Rutland. The Sapcote record of 1st June 2017 is believed to be the first record of this species in VC55.

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Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map