Formica lugubris

Behavior

Each ant is able to recognize other members of their colony by a specific odor they all carry on them. Different odors allow them to also recognize other insects and ants from other colonies. When these ants encounter members of other ant species, these are usually considered intruders and are seized and dragged into the nest. Combat between ants is common and almost always ends with death of one ant. When red wood ants encounter members of different colonies similar responses may be made, although in populations where nests have multiple queens, there is often very little aggression between members of neighbouring nests. When aggression occurs, the ants are at first startled and enter an upright body position with their mouths open. This is their way of showing threatening behavior. When in contact, members of the same colony are not threatened by each other and do not show signs of aggression. Workers are able to release pheromones that can alert others to danger nearby; this is another way these ants use odors to communicate. These ants typically mate during the month of June. Unmated winged female ants release a pheromone that will attract a male. They will both fly off into the forest and mate on the ground, usually where there are no other worker ants around. Not every ant can reproduce; reproductive males and females are larger than worker ants and have wings. After mating, the male will die and the female will lose her wings and start a new colony. Fertilized queens can take over the colonies of Serviformica ants. The queen lands on a Serviformica ant nest, finds and kills the Serviformica ant queen then takes her place. Her eggs are cared for by the Serviformica ant workers, and wood ant workers will replace them over time.

Feeding behaviour

Formica lugubris are omnivorous ants that consume a variety of different foods. Red wood ants prey on pestiferous insects and forest defoliators including spruce budworms. As well as invertebrate prey, Formica lugubris collect large quantities of honeydew from sap sucking aphids in trees. This honeydew is a major source of carbohydrate for the adult workers and represents a significant input of carbon into soils in coniferous forests where they live, equivalent to 2-6% of the carbon influx due to needle litterfall.

Nests

F. lugubris lives in massive nests that can contain up to half a million colony members. They form large, domed nests on southerly facing slopes in relatively open woodland, often along fire-breaks, tracks or in clearings. The nests have several mechanisms for keeping the internal temperature stable. The southerly orientation captures sunlight; the nest is flattened on the south side to present a greater surface area to the sun and in spring, large numbers of workers can be seen sunbathing on the nest. When warm they will go into the nest to release their heat inside. Their nests can also be home to other invertebrates, such as the shining guest ant Formicoxenus nitidulus, which is found only in the nests of F. lugubris and its close relatives.