Formica pratensis Retzius

62. Formica pratensis Retzius, 1783 Figs. 170,175, 256-262.

Formica pratensis Retzius, 1783: 75; Betrem, 1965. Formica nigricans Emery; Yarrow, 1955; Betrem, 1960.

Worker. Bicoloured with gaster, occiput and frons matt black, not shining; gaster more or less thickly pubescent. Black patch on promesonotum variable but in typical specimens clearly demarcated. Eyes thickly haired; occiput with short to medium length fringing hairs, sometimes reduced to very few. Antennal scapes without protruding hairs. Femora and tibiae fringed with hairs on extensor surfaces. Length: 4.5-9.5 mm.

Queen. As worker with all dark areas pubescent, closely sculptured and matt. Basal face of gaster and occiput with short hairs, sometimes difficult to discern or absent. Length: 9.5-11.3 mm.

Male. Matt black with pubescent gaster. Suberect hairs present on dorsum of all gaster tergites and extensor surfaces of femora and tibiae. Eye and outstanding genal hairs below eyes always plentiful and prominent. Length: 9.5-11.5 mm.

Distribution: Locally common in Denmark (only recorded from Jutland) and Southern Fennoscandia to latitude 63°. - Rare in South England. - Range: Portugal to Siberia, North Italy to Central Sweden.

Biology. This is the black backed meadow ant characteristic of rough alpine pastures but also common on woodland borders and scrubby heathland throughout lowland Europe and South Fennoscandia. Colonies are isolated single nests with one or very few queens. Jensen (1977) gives population estimates for this species in Denmark of up to 60,000 workers. Nests are smaller than with F. rufa and other species of this group and nest materials are coarser. A morphologically indistinguishable form 'pratensoides' Gösswald (1951), which is polygynous with many grouped nests, occurs locally in Germany and the Netherlands, often in shaded woodland, but has not been recorded from Denmark or Fennoscandia. Brood development begins later in the spring with sexuals normally appearing in July.