Which type of insect is not included in the caste system definition?

In a caste system, individuals within a species exhibit distinct roles and functions, often seen in social insects. Ants, honey bees, and wasps all have societies organized into a caste system where there are specialized roles such as workers, soldiers, and reproductive individuals.

Beetles, on the other hand, do not typically exhibit this caste system. Most beetle species are not social; they tend to live solitary lives rather than in structured communities with different roles. Each beetle usually has a similar role in its life cycle, which lacks the division of labor that characterizes the caste systems found in social insects like ants, honey bees, and wasps. Thus, beetles are the type of insect that does not fit into the definition of a caste system.