Formica sanguinea, or blood-red ant, is a species of slave-maker ant in the genus Formica characterized by the ability to secrete formic acid. These ants It ranges from Central and Northern Europe through Russia to Japan, China, the Korean Peninsula, Africa and also the United States. This species is coloured red and black with workers up to 7 mm long. A colony of F. sanguinea can live either as a free colony or as a social parasite of Formica species, most commonly Formica fusca and Formica rufibarbis.