Formica truncorum Fabricius

Collingwood, C. A., 1979, The Formicidae (Hymenoptera) of Fennoscandia and Denmark., Fauna Entomologica Scandinavica 8, pp. 1-174 : 139-140

57. Formica truncorum Fabricius , 1804 Figs. 224-228.

Formica truncorum Fabricius , 1804:403.

Worker. Large workers with head, alitrunk and base of first gaster tergite bright yellowish red, gaster greyish brown covered with long pubescence; smaller workers are usually darker but never with clearly marked black patches as in F. pratensis . Eyes, occiput, genae, gula, scapes and tibiae as well as whole body covered in short erect hairs. Frons with large shallow punctures; frontal triangle shining without punctures or sculpture. Funiculus in larger workers slender with segments two and three twice as long as wide. Lateral clypeal pits deep and rounded. Length: 3.5-9.0 mm.

Queen. Brightly coloured with head and most of alitrunk red or with part of ocellar region and most of scutum brownish. Pilosity and other features as in worker. Length: 8.0-9.5 mm.

Male. Black with appendages and external genitalia entirely yellowish. All surfaces covered with short erect hairs. Punctures coarse and shallow on head and alitrunk; frontal triangle shining without sculpture. Mandibles with three or four teeth. Length: 7.0-9.0 mm.

Distribution. Locally common throughout Denmark and Fennoscandia, not found in British Isles. - Range: Jura Alps to North Japan, Italy to North Norway.

Biology. This species has large spreading colonies among stones or in tree stumps with loose surface leaf litter sometimes built into a shallow loose mound. This is an aggressive acid squirting species found at the borders of woodland and in stony banks and often particularly abundant on offshore islands. F. truncorum is normally polygynous, sometimes with many small dark headed queens. New colonies may be formed by nest splitting or by the adoption of single large red headed queens by F. fusca and allied species. Males and queens occur in July and August, latter than with most members of the F. rufa group.