What is a pupa in insect development?

The pupa is a key stage in complete metamorphosis, found in insects such as butterflies, moths, beetles, and flies. During this stage, the insect is not simply resting; its body is being remodeled as larval tissues are broken down and adult structures form. In butterflies, the pupa is often called a chrysalis, while in flies and beetles it is usually enclosed in a tougher outer case. The pupal stage can last days, weeks, or longer depending on species and temperature. This transformation is one of the most remarkable processes in animal development.