What is "orussidae"

The Orussidae or the parasitic wood wasps represent a small family of sawflies (" Symphyta"). Currently, about 85 extant and four fossil species are known. They take a key position in phylogenetic analyses of Hymenoptera, because they form the sister taxon of the megadiverse apocritan wasps, and the common ancestor of Orussidae + Apocrita invented parasitism for the first time in course of the evolution of the Hymenoptera.