Formica sanguinea
Formica sanguinea, or blood-red ant, is a species of facultative slave-maker ant in the genus Formica characterized by the ability to secrete formic acid. 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, Formica japonica, Formica hayashi and Formica rufibarbis.
Raiding
Blood-red ants, F. sanguinea, are facultative slave-makers, meaning colonies can live either alone or be parasitic. This allows them to be a good model organism to study the origins of brood stealing. A fertilized F. sanguinea queen will enter the nest of the host ant species and kill their queen. She then takes advantage of the workers who tend to her and her brood. F. sanguinea workers will also raid nearby nests, stealing larvae and pupae to become future workers for F. sanguinea. The raids are also not exclusively for acquiring new workers but are sometimes predation events.Formica sanguinea has not been observed to have division of labor in which certain individuals raid or forage. However, some individuals possess more Dufour's gland compounds than others, so presumably would be more successful in during raiding.
Formica sanguinea uses scouting individuals to locate the nest that will be parasitized. Once a nest has been scouted, the raid will happen. The activities that go on during a raid are composed of digging and fighting at the target nest. Both captive workers and blood-red ant raiders are observed to be carrying the brood back to the Formica sanguinea nest. If a member of the colony is killed in the raid, individuals will take that carcass back to the nest to be eaten later. Raids were also never observed on rainy or overcast days. This is thought to be because of the detriment rain might have on terrestrial conditions and the effectiveness of alarm pheromones.
Chemical defenses
F. sanguinea uses formic acid as well as substances in the Dufour's gland as chemical defence.The substances in the Dufour's gland contain hydrocarbons such as hendecane, as well as acetates, decylacetate, and dodecylacetate.
Formica sanguinea uses the formic acid and Dufour's gland substances in conjunction with each other. The hydrocarbons in Dufour's substance serve as a wetting before the formic acid is released. Without these wetting agents, formic acid is relatively harmless to other ants. These substances dissolve the fat compounds of the epicuticle as well as enter the tracheal system to kill the opponent.