The insect industry in Korea is currently undergoing steady expansion. Among the various insects kept as pets or for educational purposes, four mantis species, including Hierodula patellifera (Audinet-Serville), Tenodera sinensis Saussure, Tenodera angustipennis Saussure, and Statilia maculata (Thunberg), are becoming increasingly popular, leading to higher demand. As we aimed to raise mantises, we collected oothecae, some of which were found to be parasitized by dermestid beetles. These parasitoids have been unequivocally identified as Thaumaglossa rufocapillata Redtenbacher based on morphological characters. A diagnosis, habitus photographs, and illustrations of diagnostic characters are provided to facilitate identification. We also present the complete mitochondrial genome sequence of T. rufocapillata for providing fundamental data for research aimed at controlling pests in the insect industry.