Red-barbed ant (Formica rufibarbis)
|Size||Length of reproductive females: 9-40 mm (2)|
Length of workers: 4.6-7.5 mm (2)
Length of males: 8.5-11.8 mm (2)
Classified as Endangered in Great Britain (3).
The red-barbed ant is classified as Endangered in Great Britain (3). Winged reproductive females and queens are generally red or reddish-yellow in colour, with protruding yellowish hairs on the body (2). Winged reproductive females have greyish coloured wings; after mating these females are known as queens, and the wings are shed. Males are blackish in colour with darker grey wings than females; their legs are yellow with a variable amount of black on the lower portions (2). Workers (non-reproductive females) are considerably smaller than reproductive males, females and queens, and their dark brown abdomens are covered in short downy hairs, which gives them a greyish appearance (2).
First discovered in Great Britain in 1896, the red-barbed ant has always been considered rare (4). Historically it has been recorded from 6 sites on the mainland, all in Surrey (4), as well as at one site on St Martins in the Scilly Isles (5). At present the species clings on at just two of the Surrey sites, at Chobham Common and Bisley (4); it was still recorded in the Scilly Isles in 1997 (3). Elsewhere it is known from Portugal, reaching east to western Siberia, and from the Middle East as far north as Fennoscandia (5).
The red-barbed ant requires warm conditions; indeed it is thought to be the most heat-loving member of the genus Formica (3). The habitats in which it occurs therefore need to be open in order to allow sufficient sunlight to filter through to ground level (3). In Britain, this ant nests in short lowland grasslands, heather or coastal heath with bare sandy ground and disturbed soil (4).
This ant has been dubbed 'the mining ant' in the past, as it nests underground or beneath stones (2). The entrance to the nest is a small hole, which may be concealed by a tussock of grass (2), nests usually extend to depths of around 30 cm below ground (5). Each mature colony can consist of 2-3 queens, and over 500 workers (5). The workers are aggressive, and attack other ant species and insects (5). The queen or queens are housed in a special chamber at the very bottom of the nest (2). In healthy colonies, winged reproductive females and males are produced each year, they fly during June and July (5), and new colonies are founded by a single queen (5). After mating, the females (now termed queens) attempt to establish a new colony. They only mate once during their lifetime, storing sufficient sperm inside their body to enable them to produce eggs for the rest of their life. Queens are the only members of the colony to reproduce; the workers feed the queen and tend to the brood. They forage alone for invertebrates, carrion, nectar and honey-dew produced by aphids (3), and can even rob prey from southern wood ant (Formica rufa) workers (2). After obtaining food, red-barbed ant workers set off in a straight line back to the nest; they do not follow scent trails like many other species of ant (2).
This species is threatened by habitat loss resulting from building development and agricultural intensification of heathland. Scrub invasion, unsuitable heathland management, trampling, excessive disturbance of nests and severe or over-frequent heathland fires also pose risks (3). Furthermore, the slave-making ant Formica saguinea is a problem, as it steals the broods of other ant species, resulting in the death of the slave provider nest (5).
A UK Biodiversity Action Plan (UK BAP) priority species, the red-barbed ant has a Species Action Plan that coordinates its conservation. This plan aims to maintain all current populations, and restore the species to sites within the former range by 2010 (3). This ant is also part of English Nature's Species Recovery Programme, and research and monitoring work has been conducted on this species under this programme (4). Three nests with queens were taken into captivity in 1999, and were being maintained. One of these nests was introduced into the wild, and further releases have been proposed in order to bolster the Surrey population. Supplementary feeding has also been undertaken and nests of the slave-making ant F. sanguinea have been removed from areas supporting the red-barded ant (4). Both of the Surrey sites are Sites of Special Scientific Interest (SSSIs), and one is a National Nature Reserve (NNR); they therefore receive a degree of protection, and management measures have been targeted at the species (3).
Information supplied and authenticated by Bryan Pinchen (independent ecologist).
- Abdomen: in arthropods (crustaceans, insects and arachnids) the abdomen is the hind region of the body, which is usually segmented to a degree. In crustacea (e.g. crabs) the limbs attach to the abdomen; in insects the limbs are attached to the thorax (the part of the body nearest to the head) and not the abdomen. In vertebrates the abdomen is the part of the body that contains the internal organs (except the heart and lungs).
- National Biodiversity Network Species Dictionary (August 2002) http://www.nhm.ac.uk/nbn/
- Donisthorpe, H. ST. J. K. (1927) British Ants: their life history and classification. George Routledge and Sons Ltd, London.
- UK BAP (August 2002): http://www.ukbap.org.uk
- Pinchen, B. J. (2002) Species Recovery Programme 2001, Action For Biodiversity: BAP Aculeates. Summary Report. Aculeate Conservation Group.
- Falk, S. (1991) A review of the scarce and threatened bees, wasps and ants of Great Britain. Nature Conservancy Council, Peterborough.