Which of the following is not a social insect?

The social insect that is not included in the given list is the housefly. Houseflies are not social insects because they do not live in colonies or work together to maintain a nest or hive. Houseflies are solitary insects that do not exhibit any social behavior. In contrast, termites, honeybees, and ants are all social insects that live in colonies or hives and exhibit a division of labor where different individuals perform different tasks to maintain the colony. For example, in an ant colony, there are workers that gather food, soldiers that defend the colony, and a queen that lays eggs. The individuals in a social insect colony work together to ensure the survival and success of the colony.