A female Mexican red-knee tarantula (Brachypelma smithi), approximately 30 yr old, was presented as an emergency at the Veterinary Medical Teaching Hospital of the University of Wisconsin for an inability to complete the molting process (ecdysis). The animal was maintained in dorsal recumbency, and ecdysis was initially assisted by gently removing retained pieces of the opisthosomal exuvium. When doing so, several slowly moving, 2–4-mm-long grayish white to whitish yellow vermiform larvae lodged between the old and new exoskeleton were exposed. These larval instars are typical of dermestid beetle larvae (Coleoptera, Dermestidae). The larval morphology and the type and distribution of setae are characteristic for Trogoderma ornatum, the ornate cabinet beetle.