The genus Laelius Ashmead, 1893 (Hymenoptera, Bethylidae) is a cosmopolitan bethylid genus with 68 valid species distributed across most zoogeographic regions worldwide. This taxonomic study on Korean species of Laelius has led to the description of four new species, namely L. aforessp. nov., L. atratussp. nov., L. sulcatussp. nov., and L. tricuspissp. nov. Additionally, illustrations of the diagnostic characteristics of each species are provided, along with an updated key for 11 Laelius species from the Eastern Palaearctic region.

Nineteen Epyris species are recorded from Korea. Ten new species: E. aequalis Lim et S. Lee, sp. nov., E. breviclypeatus Lim et S. Lee, sp. nov., E. dulicus Lim et S. Lee, sp. nov., E. finitus Lim et S. Lee, sp. nov., E. jeonbukensis Lim et S. Lee, sp. nov., E. limatulus Lim et S. Lee, sp. nov., E. longiantennatus Lim et S. Lee, sp. nov., E. mureungensis Lim et S. Lee, sp. nov., E. yetus Lim et S. Lee, sp. nov., and E. sudosanensis Lim et S. Lee, sp. nov. are described from Korea. Hitherto unknown females are described for E. fuscipes (Kieffer 1906) and E. yamatonis Terayama 1999. New synonymy is proposed for E. sauteri (Enderlein 1920) = E. formosus Terayama 2006, syn. nov. New combination is proposed for E. fuscipes (Kieffer 1906), comb. nov. (from Rhabdepyris). Seven species: E. asura Terayama 2006, E. darani Terayama 2006, E. fuscipes (Kieffer 1906), E. idaten Terayama 2006, E. niwoh Terayama 2006, E. sauteri (Enderlein 1920), and E. yamatonis Terayama 1999 are recorded for the first time from Korea. Descriptions, illustrations of diagnostic characteristics for each species are presented with a key to the Korean Epyris species.

An investigation on the habitation of Callipogon relictus Semenov, 1899 in Gwangneung forest was carried out, where the Korea National Arboretum is located. In an investigation spanning the last eleven years (2007–2017), 22 emergence holes, nine pupal chambers, six adults, and two larvae of C. relictus were identified. In this study, biological information about habitation of C. relictus is provided by comparing and combining the results of this investigation with a survey conducted in Ussurisky Nature Reserve, Russia, in 2015. The distribution is also reviewed to include the Korean Peninsula and a new location of South Korea is added to the distribution for C. relictus.

For the first time, Bethylus Latreille, the type genus of Bethylidae (Hymenoptera, Chrysidoidea, Bethylinae), is reported from the Korean Peninsula based on the discovery of a new species, Bethylus colligatussp. nov., which was collected in Gangwon Province near the Demilitarized Zone. This new species is described and illustrated. A phylogenetic analysis was conducted using mitochondrial cytochrome c oxidase subunit I sequences from common Bethylus species to better understand the evolutionary relationships within the genus. The resulting phylogeny supports the distinction between B. colligatussp. nov. and other species. Additionally, a key to the species of Bethylus in East Asia is provided.

Pararhabdepyris Gorbatovskii (Hymenoptera: Bethylidae) is newly recognized from South Korea. The genus can be easily recognized from other genera in Scleroderminae by having the head wider than it is long, the antenna with 10 flagellomeres, the clypeus with short projected median lobe, and the metasomal tergite II longer than the combined length of remained tergites. Description and illustrations of diagnostic characteristics of Pararhabdepyris paradoxus Gorbatovskii are provided. In addition, the present paper provides the first host record of Allobethylus Kieffer of Scleroderminae from the world. A revised key to genera and species of South Korean Scleroderminae is also presented

Pararhabdepyris Gorbatovsky is a small genus within Bethylidae, currently comprising only six valid species worldwide. A new species, Pararhabdepyris directus Lim sp. nov., is described and illustrated from South Korea. It appears closely related to P. paradoxus, is characterized by the combination of the following characters: the basal two-thirds of the scape are dark castaneous, coxa and femora are dark castaneous, the median and submedian areas of metapectal-propodeal disc are rugulose, and the transverse posterior carina of metapectal-propodeal complex is straight. An updated key to the world species of the genus are presented.