A group of ants is called as :

Colony

The correct answer is colony. A group of ants is called a colony. The word "colony" is a collective noun, which means it refers to a group of animals of the same species that live together in a structured society.

The other answer choices are incorrect. Pack refers to a group of wolves or other wild animals, host refers to a group of people or animals that are gathered together, and band refers to a group of people or animals that are traveling together.