Formica rufa

[2] It is native to Eurasia, with a recorded distribution stretching from the middle of Scandinavia to the northern Iberia and Anatolia, and from Great Britain to Lake Baikal,[3][2] with unconfirmed reportings of it also to the Russian Far East.

[3] Formic acid was first extracted in 1671 by the English naturalist John Ray by distilling a large number of crushed ants of this species.

Nests of these ants are large, conspicuous, dome-shaped mounds of grass, twigs, or conifer needles,[4] often built against a rotting stump, usually situated in woodland clearings where the sun's rays can reach them.

[4] F. rufa is highly polygynous and often readopts postnuptial queens from its own mother colony, leading to old, multigallery nests that may contain well over 100 egg-producing females.

Nuptial flights take place during the springtime and are often marked by savage battles between neighbouring colonies as territorial boundaries are re-established.

These ants' primary diet is aphid honeydew, but they also prey on invertebrates such as insects and arachnids;[4] they are voracious scavengers.

This demonstrates that a chemical stimulus from the cocoons seems to be of paramount importance in prompting adoption behaviour in worker ants.

Wood ants have been shown to tend and harvest aphids and prey on and compete with, other predators for food resources.

By observing skirmishes and trail formation of wood ants, the territory surrounding each nest differs between seasons.

Permanent foraging trails are reinforced each season, and if an ant from an alien species crossed it, hostile activity occurs.

Strong defensive measures include guarding entrances to tunnels and having routine patrols of the areas to watch neighbouring nests.

[21][22][23] By leveraging the antimicrobial properties of the resin, wood ants are adequately ensuring and sustaining the health of their colonies.

[23][24] Wood ant nests are vulnerable to rapidly spreading microbial loads due to the dense population and organic debris accumulation within large, complex structures.

[21][22][23] Besides antifungal and microbial defense, resin provides value structural integrity to the nest and a protective barrier from potential intruders and predators.

[18][27] The stickiness and sometimes toxicity of the resin aid in providing a protective barrier against small arthropods and mites that may attack the nest.

[16][18][21][28] Polygyny in wood ants (Formica genus) is a colony's social structure that contains multiple reproducing queens.

Polygyny may have evolved to enhance colony survival in unstable environments as it allows wood ants to disperse across larger areas by establishing interconnected nests with several queens.

[29] Polygyny may have evolved to enhance colony survival in unstable environments as it allows wood ants to disperse across larger areas by establishing interconnected nests with several queens.

These polygynous colonies have a more complex social hierarchy and can be more successful in certain ecological contexts because of the combined reproductive efforts of several queens.

[32] Through polygyny, the wood ant colonies exhibit reduced levels of relatedness between workers, which can have negative and positive implications.

Besides higher genetic diversity, a positive implication is that the colony has faster growth in numbers due to multiple queens producing broods.

A caterpillar being bitten by F. rufa
Patrolling F. rufa
Detail of the head. Picture from antweb.org casent0173863
F. rufa nest
F. rufa nest in meadow near Rila, Bulgaria