Narrow-headed ants ©John Walters

Narrow-headed ant

Scientific name: Formica exsecta

A very rare ant, once found on heathland across southern England but now restricted to Scotland and Devon. It constructs distinctive thatched nests in open areas at the edges of scrub, and forages for aphid honeydew on nearby plants.

Species information

Statistics

Length: up to 10mm; queens ~12mm

Conservation status

Priority Species under the UK Post-2010 Biodiversity Framework (NERC Act Section 41 Species of Principal Importance). UK Red Data Book. Scottish Biodiversity List

When to see

May to October

About

The Narrow-headed ant is one of the rarest ants in the UK. Never common, it has been lost from most of its few former sites and is now restricted to Devon and Scotland. It constructs small and distinctive mounded nests, topped with a thatch of nibbled grass or heather fragments. Nests are orientated towards the sun, in open areas at the edges of scrub. Narrow-headed ant colonies are much smaller than those of wood ants, numbering around 1000 individuals. They often forage for aphid honeydew on surrounding plants, such as gorse, birch and buckthorn, but also prey upon and scavenge many different types of invertebrates. The winged males and queens take to the air in a nuptial flight early in the morning on certain days in July-August, when conditions are right, but disperse only short distances of 60-120m, if at all.

How to identify

Related to, but separate from, wood ants, this is a medium-sized black and red ant, with a characteristic notch in the back of its head.

Distribution

Found at very few sites in the UK, with populations now confined to the Scottish Highlands and a single heathland in Devon.

Habitats

Heathland and moorland

Did you know?

New nests can be established in different ways: either a queen must take over the nest of another ant species (Formica fusca or Formica lemani), or satellite nests can bud off from a main nest and become independent. Some nests may have multiple queens, and a colony can have several nests. Queens can live on average for 27 years.

How people can help

The Wildlife Trusts are working to restore and protect our heathlands by promoting good management, clearing encroaching scrub and implementing beneficial grazing regimes. This work is vital if these habitats are to survive; you can help by supporting your local Wildlife Trust and becoming a member or volunteer.

Devon Wildlife Trust is working in partnership with Buglife as part of the ‘Back from Brink’ project, to safeguard the narrow-headed ant's future in England. The aim is to establish populations at former and new sites nearby, and undertake suitable habitat management to create the open scrub edge conditions the ant needs for nesting and foraging. There is also research and monitoring undertaken. Much of this work is carried out by volunteers. By volunteering you can help too, making new friends, learning new skills, and getting a chance to make new discoveries about one of the rarest species in England.