Formica rufa, also known as the red wood ant or carpenter ant, is a species of ant found in Europe and Asia. These ants are known for their large size, ranging from 6 to 12 mm, and fiery red color. Other common names for Formica rufa include wood ants, mound ants, and thatching ants. In the UK, they are sometimes referred to as northern wood ants. Formica rufa are known for their impressive nest-building skills, constructing large dome-shaped mounds made of plant material and soil. They are also known for their aggressive behavior, particularly when defending their nests. Overall, Formica rufa is a fascinating and important species in the ecosystem.