Red Wood Ant

The Red Wood Ant is a large, conspicuous ant species in the family Formicidae, well known for constructing some of the most impressive ant mounds found in temperate forests. These mounds, built from pine needles, twigs, and other plant debris, can persist and grow for many years, sometimes housing colonies of hundreds of thousands of workers.

As a member of the Formica rufa group, this species is a keystone predator within woodland ecosystems, foraging widely across the forest floor and up into tree canopies in search of prey and honeydew. Its large, thriving colonies make it one of the more ecologically influential insects of European coniferous and mixed forests.

Red Wood Ants are also notable for their defensive spray of formic acid, a chemical they can eject when disturbed, which along with biting is their primary means of colony defense rather than a true sting.

• Reddish-brown head and thorax contrasting with a darker brown to black abdomen.
• Large for an ant, with a stocky build and dense, short hairs on the body.
• Builds large, dome-shaped mounds of pine needles, twigs, and soil, often over a meter tall.
• Workers travel along well-worn foraging trails radiating out from the mound, sometimes climbing trees to tend aphids.
• Lookalikes: other Formica species share similar coloring; mound size and the reddish thorax against a darker abdomen are useful identifying features.

Native to much of Europe and parts of temperate Asia, the Red Wood Ant favors coniferous and mixed woodlands, especially pine and spruce forests with clearings that receive good sunlight for mound warming. Mounds are typically built at the base of trees or stumps and can be found in the same location for many years. Foraging activity is heaviest from spring through early autumn.

Colonies forage aggressively and cooperatively, with worker trails extending many meters from the mound to gather insect prey, both alive and dead, as well as honeydew from aphids tended on nearby trees. Workers can bite and spray formic acid from the tip of the abdomen as a defensive response when the mound is disturbed. The species plays an important ecological role in controlling populations of other invertebrates within the forest and in aerating and enriching soil around the nest.

Red Wood Ants undergo complete metamorphosis, with eggs developing into larvae, pupae, and finally adult ants, all tended by workers within the mound. Colonies can be founded by a single queen or, in some populations, form interconnected supercolonies with multiple mounds and queens. Winged reproductives are produced seasonally and disperse to found new colonies, while established mounds can persist and expand for many years, with the ants overwintering in a dormant cluster deep within the mound.