Lasius brunneus

35. Lasius brunneus (Latreille, 1798) Figs. 131,132.

Formica brunnea Latreille, 1798:41.

Worker. Bicoloured with gaster dark brown contrasting with testaceous or pale reddish brown head and alitrunk. Pubescence and body hairs sparse. Occipital hairs restricted to median area of back of head only. Scapes and tibiae never with erect hairs. Back of head flat or feebly concave. Frontal triangle and frontal furrow distinct, ocelli small but always clearly visible. Length: 3.2-4.5 mm.

Queen. Dark brown. Head comparatively massive, nearly as broad as alitrunk. Fore-wings partly infuscate. Ocelli conspicuous. Pilosity and other head features as worker. Head width 1.50-1.65 mm. Length: 8.0-9.0 mm.

Male. Dark brown. Head large with conspicuous frontal suture; mandibles with well marked pre-apical cleft. Dorsal margin of petiole deeply concave. Fore-wings partly infuscate. Length: 3.5-4.5 mm.

Distribution. Denmark: LFM, local; Sweden: Sm. - Dlr; Norway: 0, B, AK, VE and TE. - Not recorded from Finland. - Locally common in Central South England. - Range: Spain to Crimea and West Himalayas, Italy to Sweden.

Biology. This species nests in the interior of old trees, chiefly oak, but has also been recorded from hedgerows. It is fugitive and non-aggressive, rapidly dispersing on disturbance and because of its cryptic habits may be somewhat under-recorded. In Norway and Sweden it has frequently occurred nesting in the timbers of old houses and farm buildings, where its populous colonies may be difficult to dislodge. It chiefly tends tree aphids including the large bark feeding Stomaphis. Single queens initiate colonies in the crevices of old trees but may also be accepted back into the mother nest after the mating flight which occurs in June and early July.