Creature of the day: The Wood Ant 🐜🐜 🔥🔥 Formica is a genus of ants of the subfamily Formicinae, including species commonly known as wood ants, mound ants, thatching ants, and field ants. Formica is the type genus of the Formicidae, and of the subfamily Formicinae. The type species of genus Formica is the European red wood ant Formica rufa. Ants of this genus tend to be between 4 and 8 mm long. Ants belonging to the Formica genus possess a single knob or bump located between their thorax and