Chalcid wasps (Hymenoptera: Chalcidoidea) comprise over 22,500 species worldwide and are estimated to more than ten times as specious. They are therefore one of the most species rich, but at the same time most understudied group of insects. This is despite their key role as regulators due to their parasitoid life style. Part of my research aims to assess the chalcid fauna in Europe via DNA-barcoding (QT2: Biodiversity patterns: species and their distribution) to identify unknown and taxonomically problematic species. I also focus on studying the Cretaceous chalcid fauna (QT1: Integrative phylogeny and evolution of life strategies), to better understand extant diversity.