Formica rufa Linne

58. Formica rufa Linne, 1761

Figs. 169, 171,229-235.

Formica rufa Linne, 1761:426; Yarrow, 1954 (redescription).

Worker. Bicoloured red and brownish black with variable degree of depth and size of dorsal dark patch on head and promesonotum. Eyes usually with a few microscopic hairs. Long erect hairs more or less abundant on gula, clypeus, dorsum of head, alitrunk, scale and gaster but never on scape nor on posterior border of occiput. Occasional to few suberect hairs on extensor surfaces of hind tibiae and femora. Frontal triangle reflecting light but often in part with micropunctures. Frons somewhat shining with widely spaced indistinct fine punctures and scattered coarse punctures; coarse and fine punctures widely spaced on disc of first gaster tergite. Funiculus segments two and three always less than twice as long as wide. Length: 4.5-9.0 mm.

Queen. Bicoloured with whole of scutum, gaster and part of occipital area of head normally dark. Scutellum and gaster distinctly shining, never dull. No erect hairs on posterior border of occiput and normally entirely absent on basal face of [[...]] Pubescence on gaster short and sparse. Micropunctures interspersed with [[...]] punctures on disc of first gaster tergite always widely spaced. Length: 9.5-11.0 mm.

Male. Black with most of appendages and genitalia paler. Eyes with few or many erect hairs. Genae below eyes normally without outstanding hairs. Dorsum of head and alitrunk with suberect hairs. Sparse suberect hairs visible at dorsolateral margins of all gaster tergites. Upper margin of hind femora without row of short hairs. Frontal triangle shining with or without micropunctures. Length: 9.0-11.0 mm.

Distribution. Generally common throughout Denmark and Fennoscandia north to approximately latitude 63°. - Locally common in South England and Wales, more local in North England.

Biology. This is the common wood ant of most of lowland Europe building large hill nests of leaves and twigs. Nests may be isolated or in small groups, normally with many queens, up to 100 or more. Various estimates of numbers of workers in a populous nest range from 100,000 to 400,000. This is an aggressive acid squirting but somewhat clumsy species. Foraging trails radiating from a large nest may be up to 100 m or more usually orientated toward suitable aphid bearing trees. Prey is taken somewhat unselectively from both trees and forest floor with any insect, arthropod or earthworm taken back as food to the nest although the main diet as with all species of this group is aphid honey dew. These ants mass in tight clusters on the top of the mound in the early spring sunshine. The first queen laid eggs develop into alate sexuals which fly off the nest early in the summer from May until early July. New nests arise from colony splitting in the spring but occasionally single queens may secure adoption in nests of Formica fusca.

A monogynous form of F. rufa occurs in continental Europe and probably locally in Sweden but has never been found in England. This is the Formica rufa rufa of Gosswald (1941). Average worker size of this form is generally large and samples are usually conspicuously hairy. Many males from such isolated colonies in the Netherlands may have one or more coarse hairs protruding from the genae below the eyes and very occasionally queens may have very short sparse hairs on the basal face of the gaster but all such individuals have the widely spaced puncturation of true F. rufa and although workers may have a few hairs on the upper surface of the hind femora they never form a close fringe as in other species. This form has also sometimes been referred to as F. piniphila Schenck, 1852. Although generally monogynous, similar hairy specimens occur on the coastal dunes of the Netherlands in polygynous colonies.