Formica truncorum

Appearance

"F. truncorum" ants are characterized by a grey-brown gaster and bright yellow-red head and thorax. The smaller workers are normally darker in color. They can be distinguished from other species of "Formica" by the small erect setae covering their entire body. Workers can range in size from 3.5 to 9.0 mm.

Behavior

"F. truncorum" is a member of the insect order Hymenoptera, which contains the majority of the eusocial insects. "F. truncorum" demonstrates some characteristics specific to eusociality. There is cooperative rearing of young, which is thought to provide a sort of 'life insurance' for the female's brood. If the female were to die during the rearing process, others would take her place to finish raising the brood. The value of this cooperation may justify the cost. Another defining characteristic of eusociality is the evolution of specific castes within the species, some of which are sterile. Castes in "F. truncorum" include the drones, the winged male ants with the sole purpose of reproducing, the queen, who sheds her wings after the nuptial flight, and the sterile workers which can vary in size depending on specialized tasks.

Eusocial behaviour is thought to have evolved as a result of kin selection within monogamous colonies. In multiply mated colonies, the relatedness between siblings is lowered, which diminishes the benefits of altruistic behaviour within the colony. Only in monogamous colonies would the relatedness between individuals in a colony remain high, which could allow the benefits of eusociality to be justified by Hamilton's rule.

Habitat

"F. truncorum" is located in many places worldwide, such as northern Japan, the Jura Mountains and many regions from Italy to Norway. The colonies, which can be polygynous and often polydomous, are spread out in regions of woodland borders, where the ants will make their nests in tree stumps.