Formica aquilonia Yarrow, 1955

Description and notes

This species is outwardly similar to others in the Formica rufa-group and is commonly known as the Scottish wood ant.

Distribution

Formica aquilonia is restricted to the Scottish Highlands and two localities in Co. Armagh in Ireland. In Scotland the species is recorded from around the Firth of Clyde, through the Central and Western Highlands, Tayside and the Grampians, as far north as Ross and East Sutherland. It is also recorded from the Isle of Skye and reported from the Isle of Arran. Its range in Scotland overlaps that of the northern wood ant, Formica lugubris and so care is needed to distinguish these species. Where it is found, F. aquilonia may be locally common and it is probably under-recorded in the remoter parts of Scotland. The range of the species extends across northern Europe and Scandinavia to Siberia, it is also found in cooler mountain regions of central Europe and Asia.

Status (in Britain only)

Formica aquilonia is listed as Notable B in Falk (1991) (now known as Scarce (Nb)), and some populations may be threatened by loss of suitable habitat or inappropriate woodland management.

Habitat

This species is associated with undisturbed Caledonian pine forest and mature birch groves; it also occurs along woodland ride s and clearings in suitable plantation forest.

Flight period

Males and gynes can be found in the nests from May to early July and mating flights usually occur in June or July. New nests are often formed by fission from the parent colony, which can contain many queens. More isolated new colonies may be founded by a group of queens and some stray workers or possibly through semi-social parasitism of other Formica species.

Foraging behaviour

Formica aquilonia forms long trails to trees bearing honeydew-producing Homoptera. The species is highly dependent on these bugs which provide the majority of their carbohydrate and some of their protein requirements. The availability of a suitably rich supply of Homoptera and their host trees is probably a major limiting factor in the distribution of F. aquilonia. Other living or dead invertebrates encountered in the tree canopy or woodland floor will also be taken for food.

Nesting biology

Formica aquilonia builds very large mound nests from vegetation fragments; these nests are rarely isolated and are often linked by long trails to neighbouring mounds so forming one huge colony. The nests are usually built on free-draining soils or slopes with some exposure to the sun, although F. aquilonia appears to be more shade tolerant than other wood ants.

Parasites and commensals

In Britain, no parasitic ant species are known to be associated with F. aquilonia, although the commensal species Formicoxenus nitidulus has been recorded from its nests.

Author of profile

S P Hoy

Year profile last updated

2001