What is the pupal case formed by insects undergoing complete metamorphosis known as?

The correct term for the pupal case formed by insects undergoing complete metamorphosis is referred to as a "pupa." During this life stage, which is a key part of complete metamorphosis, insects transform from the larval stage to the adult stage. The pupa serves as a protective casing, allowing the insect to develop and undergo significant physical changes.

In some cases, the pupa can be encased in a structure that may be more specifically named, such as a chrysalis (in butterflies) or a cocoon (in many moths). This structure provides not only protection but also a controlled environment for the various transformations that occur within.

Other options like "larval shell" and "pupa body" do not accurately describe the biological structure involved in this stage of development, and "metamorphosis capsule" is not a commonly recognized term in entomology. Thus, the use of the term "insect case" to describe the pupa is generally accepted, as the case protects the developing insect during this critical phase.