A. Spalding

This account builds on the chapter written by P. and J. Mellor in 1997. There has been considerable work carried out since then by Ian Beavis on the Isles of Scilly, a generally greater interest in ant recording and revised identification of some species, with greater clarity on the status of Stenamma westwoodii within the region. The revision of the status of Lasius niger and Lasius alienus, published in 1992 by Seifert, is now more widely available following a publication by Glenda Orledge (2003), so that we now know that Lasius platythorax (split from Lasius niger) may occur in Cornwall and Lasius psammophilus (split from Lasius alienus) does occur in both Cornwall and the Isles of Scilly.

In the British Isles there are nearly 50 native species of ant currently recorded. Since 1900, some 30 or so species of ant have been recorded in Cornwall and the Isles of Scilly; 21 of these have been recorded since 1980 (adding up to 22 if Lasius platythorax is included). There are two RDB species: Narrow-headed Ant Formica exsecta (last known from a 1963 record) and Red Barbed Ant Formica rufibarbis (found on the Isles of Scilly). There are two introduced ants, cosmopolitan tramp species, which appear unable to establish themselves outdoors due to the cold wet Cornish winters. There is a single record for the Argentine Ant Iridomyrmex humilis (Mayr) from ships and warehouses in Falmouth in 1984 and one post-1960 record for Pharaoh’s Ant Monomorium pharaonis Linnaeus from Penzance Hospital (this species is common throughout the British Isles in heated premises such as hospitals and bakeries).

The most species-rich sites are those on south and south-west facing slopes and cliffs with a diverse flora and short vegetation, where high soil temperatures provide suitable habitat for brood incubation. The deliberate introduction of Myxomatosis to Britain in 1953 led to a decrease in rabbits and a consequent decline in short rabbit-grazed turf suitable for warmth-loving species such as Myrmica sabuleti (well-known for its association with the Large Blue butterfly) and Tetramorium caespitum. Ants associated with cooler conditions, such as Formica fusca, Myrmica rubra and M. ruginodis, thrive in the abundant scrub that now occupies much of the former rabbit-grazed turf.

Information for the following accounts comes from Barrett (1979), Collingwood (1979), Ian Beavis’s reports from the Isles of Scilly and ERCCIS. The current RDB and Notable status is taken from Falk (1991). Excellent photos of many of the British species are available in the Ants of Surrey (Pontin, 2005). Helpful comments came from Ian Beavis, Graham Collins, Paul Gainey, Rosemary Parslow and John Walters.

1. RDB species

Formica exsecta

Formica rufibarbis Red Barbed Ant

Solenopsis fugax The Small Raider Ant

2. Notable species

Ponera coarctata The Indolent Ant

Temnothorax albipennis A Slender-bodied ant

Tapinoma erraticum The Erratic Ant

3. Locally Scarce species

Myrmica lobicornis

Myrmica sulcinodis

Leptothorax acervorum

Stenamma debile

Myrmecina graminicola

Lasius mixtus

Lasius psammophilus

Lasius umbratus