Ants are insects of the Formicidae family. They are related to bees and wasps.
What do you call a group of ants? A bunch of ants are called a colony or an army. I guess they are a colony when peacefully caring for their larvae and an army when they are running up your leg.
Perhaps they are a colony when you are watching them on the nature channel but they are an army when they are in your backyard? Relax, I won't continue.