In our yard we have a couple of ant hills that are home to a unique species: the thatching ant. They are common in the forests and grasslands around Missoula but few people know how interesting they are. Thatching ant hills get up to almost 3 feet tall and may be used for many years. Ants build their hills under trees or shrubs like sage on the prairies, where they are protected from weather.
On hot days, you will see the colony busy with many ventilation holes open. This allows hot air to escape so the hill stays cool inside- just like people do to cool off their houses in the summer. This keeps the larvae and the queen from getting too hot.