Scelionidae are idiobiont endoparasitoids exclusively attacking the eggs of diverse insect groups like Lepidoptera, Heteroptera, Diptera, Coleoptera, Mantodea, Neuroptera, as well as araneomorph spiders. Both Platygastridae and Scelionidae were originally described by Haliday in 1833 and 1839, respectively. Scelioninae, with 16 tribes, is the largest of the three subfamilies, comprising nearly 70% of the species of Indian Scelionidae. Teleasinae are distinguished from Scelioninae mainly by the venation of their fore wings. Platygastridae is considerably smaller in size, compared to Scelionidae. Compared to Sceliotrachelinae, Platygastrinae are slender and elongate. Teleasinae attack the eggs of carabid beetles, while the host groups of Scelioninae are mainly Orthoptera and Heteroptera. A few species of egg parasitoids belonging to Trichogrammatidae, Scelionidae, and Mymaridae are known to be phoretic on their hosts. Along with members of Trissolcus Ashmead, other scelionids too attack the eggs of several heteropteran families like Pentatomidae, Scutelleridae, and Lygaeidae.