Formica exsecta Nylander

Collingwood, C. A., 1979, The Formicidae (Hymenoptera) of Fennoscandia and Denmark., Fauna Entomologica Scandinavica 8, pp. 1-174 : 129-130

50. Formica exsecta Nylander , 1846 Figs. 201, 202,208,212, 214, 217.

Formica exsecta Nylander , 1846a: 909.

Worker. Bicoloured with gaster dark brown, rest of body reddish with varying amount of dark colour on head and promesonotum. Head strongly excised posteriorly; maxillary palps 6 segmented, long as half head length. Scale strongly emarginate. Eyes with very distinct erect hairs which are normally abundant. Body pilosity variable - erect hairs on all gaster tergites, on clypeus and on dorsum of head, sometimes also on occipital margins. Clypeus not impressed. Length: 4.5-7.5 mm.

Queen. As worker, head normally somewhat darker and promesonotum more or less dark brown. Head pilosity very variable but eyes always distinctly haired. Length: 7.5-9.5 mm.

Male. Dark brownish black, appendages yellowish to brown. Head broadly emarginate, scale excised. Eyes with distinct but sparse hairs. Maxillary palps 6 segmented, long. Length: 6.2-9.0 mm.

Distribution. Throughout Denmark and Fennoscandia, very common. - Local in Southwest England and Scottish Highlands. - Range: Central Spain to Urals, Appenines to extreme north of Europe.

Biology. This is an active aggressive species building mounds of leaf litter in open woodland, moorland and rough pasture. On disturbance the ants swarm out and bite vigorously. Nests may contain a thousand or more workers with more than one queen. They are often grouped with amicable interchange of workers between each. F. exsecta is mainly aphidicolous tending aphids on Juniperus, Picea and other trees but is also predaceous. Colonies extend by nest splitting but single queens also start colonies by securing acceptance in nests of Formica lemani or F. fusca . Alatae occur in July.