From ZooTerms (Dictionary of Invertebrate Zoology)
Arthropoda: Insecta) 1. In certain families of Diptera, a case formed by the hardening of the next to the last larval skin, in which the pupa is formed; pupa coarctate. 2. Sometimes used in a few parasitic Hymenoptera and Coleoptera for the cast exuviae held at the posterior end of the larval body. 3. In Diaspidine scales, used for the scale of mixed exuviae and wax or for the female enclosed in the unruptured cuticle of the last larval stagepuparium (noun; Latin pupa, puppet): (
See also: pupillarium.