soldier

In social insect colonies, a "soldier" is a specialized caste of individuals, typically sterile, whose primary role is the defense of the colony. These soldiers are distinct from other members, such as workers or reproductives, through anatomical or morphological differences.1

In termites, soldier castes are crucial for protection against predators, often ants. They possess large, hardened heads and powerful jaws (mandibles) for combat. Some species have evolved chemical defenses, secreting sticky or toxic liquids, or have developed specialized head structures like a snout to spray defensive substances. While most soldier termites have both workers and soldiers, some species lack a distinct soldier caste, relying on other defense mechanisms. The term "soldier" is also used for specific types of flies (Stratiomyidae) and beetles (Cantharidae), but these are distinct insect families and not related to the caste system of social insects.234