Ants are everywhere. They are dominant components in much of the terrestrial world as premier soil turners, predators of other arthropods, dispersers of seeds and, in neotropical regions, the attine leafcutter ants must be considered the major herbivores in rainforests and cultivated fields. Approximately 14 000 species of ants are known to science, but the number continues to grow and it is hard to say how many species actually live on our planet.

Science has revealed many unique and fascinating natural histories for a large diversity of ant species, but certain groups stand out. Clearly, the pinnacles in ant evolution include the army ants of the neotropics and the driver ants of Africa, the tree-dwelling weaver ants of Africa, Asia and Australia, the fungus growers of the tribe Attini in Central and South America, and the migrating herdsmen of the genus Dolichoderus of the Malaysian peninsula. The mound-building wood ants, the so-called Formica rufa group, must also be considered one of the pinnacles of ant evolution.

In 1960, as an advanced biology student at the University of Würzburg in Germany, I was charged with the wonderful task of spending about 2 months in Finland collecting wood ants in forests from the south to the north beyond the Arctic Circle to send these samples to the Institute of Applied Zoology at the University of Würzburg. The general abundance of Formica mounds in Finnish forests, especially in primeval forests, was most impressive. Unfortunately, wood ant mounds are now rare or totally absent in most Central European forests mostly due to negligence, despite the fact that entomologists had already recognised in the nineteenth century the decisive role wood ants play in biological pest control. The undisputed founder of forest entomology, Julius Theodor Christian Ratzeburg (1801–71), observed that the surrounds of wood ant mounds resembled green islands during pest insect outbreaks. According to Auguste Forel (1848–1931) the inhabitants of a single large Formica rufa nest can retrieve 100 000 insects in one day; this adds up to 10 million prey insects in one summer. These numbers are astonishing and perhaps somewhat exaggerated, or perhaps not? In any case, mound-building wood ants are very beneficial to the health of forests, and therefore Ratzeburg proposed to propagate and resettle Formica nests by artificial fission.