HYMENOPTERA > APOCRITA | Aculeata > Formicidae > Formicinae > Formicini

A dull black species with workers that average around 5-7mm and queens that are only marginally larger. The head, alitrunk and gaster are a uniform dark greyish to brownish-black colour with only a slight shiny aspect. The legs are distinctly brownish and noticeable paler than the rest of the body. The back ridge of the head and the top of the thorax are virtually hairless, perhaps with one or two weak pronotal hairs, but without any stout upstanding hairs. This particular feature is an important identification aid in central areas of the country where there may be an overlap with Formica lemani.

Across the south though, and certainly within my general area, Formica fusca can safely be regarded as the default large black ant found in woodland clearings, rough grassy areas or on heathland. The species is active and more likely to be seen through the warmer months from May to September, with the alates - winged males and potential queens - emerging and mating from late June to early August.

Formica fusca nest under stones or logs, or in tree stumps and, within well occupied areas, nest density can be high. Each nest usually contains a single queen and a few hundred workers, possibly up to a thousand once the nest is established. Some nests may be 'facultatively polygynous' with two or three queens, but when this situation occurs, the queens are known to coexist amicably. Individual workers may be seen hunting and foraging for food both on the ground and in vegetation. They are omnivorous, feeding on various small invertebrates as well as seeking out aphid honeydew. Workers will actively defend aphid colonies close to their nest site from being predated by other insects as the honeydew is a valuable food source.

Nests are often raided by the slave-maker ant Formica sanguinea if present in the same general area.