The family Platygastridae is a large group of parasitoid wasps, generally have a small body size (1-2mm). Platygastidae comprised of 5 subfamilies (Platygastrinae, Sceliotrachelinae, Scelioninae, Teleasinae, and Telenominae). Until know 6,049 species in 265 genera are reported around the world except polar regions and 96 species in 26 genera are reported from Korea. This study contains general information of Platygastrid wasps as a candidate of effective natural enemy, also provide high resolution photography to identify Korean Platygastid wasps at the genus levels.

The genus Trissolcus Ashmead is an egg parasitoid of the family Pentatomidae, of which species are used for biocontrol agents for sting bug pests. Until now, 8 species of Trissolcus were recorded from South Korea. In this study, two species, Trissolcus plautiae (Watanabe) and T. elasmuchae (Watanabe, 1954), are newly recognized from Korean peninsula. Diagnosis, photographs and key to species are provided.

The former Scelionidae (sensu stricto) is considered to be a part of Platygastridae, recently. During the parasitic wasp collecting with yellow pan trap, aiming at investigating promising biological control agents which attack on plantbug pests for soybean cultivation, one new species and one unrecorded scelionine species were identified. Opisthacantha albertoi sp. n. was collected from central part of korean peninsula. It is very unique by its yellowish body, compared with the black of the most recorded korean scelonine species. It has a long ovipositor which is 1.3 times longer than body length. It was named after the late Dr. S.-B. Ahn, the noctuid specialist. The unrecorded Tiphodytes gerriphagus (Marchal) was famous for its extremely extraordinary habit of diving for Hymenoptera to attack the eggs of gerrid hosts (Gerris, Trepobates spp.). It was collected nationwidely in Korea. As a result, two genera are newly added in korean scelionine fauna and korean Scelioninae is composed of eight species in five genera in total.

Platygaster robiniae Buhl and Duso (Hymenoptera: Platygastridae) is a gregarious koinobiont endoparasitoid of Obolodiplosis robiniae (Haldeman) (Diptera: Cecidomyiidae). The life cycle and development of the parasite is described. P. robiniae proves to be an egg-larval parasitoid, parasitizing eggs of O. robiniae and emerging from host larvae, and eggs of the wasp develop monembryonically. Its egg and embryonic stages are prolonged to some extent. The parasitoid undergoes only one larval instar, and total development time from egg to adult takes about 28 days to complete. The life cycle of a parasitoid generation is perfectly synchronized with that of the host: the waps emerges near the emergence time of the host, so that they can parasitize host eggs.