Abstract
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.afores sp. nov., L.atratus sp. nov., L.sulcatus sp. nov., and L.tricuspis sp. 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.