Formica pressilabris Nylander

53. Formica pressilabris Nylander, 1846 Figs. 206,207,211,215.

Formica pressilabris Nylander, 1846a: 911.

Worker. Bicoloured; head and scale deeply excised. Eyes bare. Maxillary palps very short, 5 or 6 segmented. Erect hairs on dorsum restricted to anterior margin of clypeus and gaster tergites 4 to apex. Clypeus transversely impressed below mid line, with a distinct concavity when seen i profile. Gaster pubescence sparse with hairs slightly shorter than their interspace - general appearance moderately shining. Length: 4.2-6.0 mm.

Queen. More or less evenly dark brown with propodeum and under body lighter, very shining, rest as worker. Size small. Length: 4.5-5.5 mm.

Male. Dark brown, somewhat shining. Mesonotum clothed in short fine hairs. Erect hairs on gaster restricted to apical segments. Pubescent hairs sparse about as long as interspace. Length: 4.5-6.0 mm.

Distribution. Local in South Norway. Locally abundant in Denmark, Sweden and Finland as far north as Med. and Ks, respectively. - Not found in British Isles. - Range: widely distributed from Spanish Pyrenees to Siberia, Italy to Central Fennoscandia.

Biology. This species constructs football size mounds of grass litter in dry pasture and on banks in open woodland. Usually two or more nests are found together with up to two thousand workers and several queens in each. In Poland F. pressilabris has been extensively studied by Czechowski (1975); there the species is mainly found in open meadows in polygynous polycalic colonies of many nests. The chief food source was the exudate of species of aphids feeding on herbage and very little predatory activity was observed. In Fennoscandia nests observed have usually been either single or more commonly in groups of up to five. Although similar in appearance to F. forsslundi this is a dry habitat species and does not normally occur in the neighbourhood of mires. Alatae occur in July and August.