A detailed study of ovipositor morphology in Ctenopelmatinae (Ichneumonidae) is provided and used to assess the evolutionary patterns of the Ophioniformes, Ctenopelmatinae, and more specifically the tribe Pionini (Ctenoplmatinae). Ovipositor morphology also provided a foundation for a generic revision of Hodostates Foerster, 1869. Monophyly of Ophioniformes, as defined by Gauld and Wahl, is not supported by research provided in this thesis. Morphological characters previously used to unite Ophioniformes are also found in non-ophioniform subfamilies, leaving the ophioniformes without a morphological synapomorphy. Research on the tribe Pionini, as currently defined by Townes, led to the hypothesis that pionines are polyphyletic with likely evolutionary affinities including, but not limited to, Mesoleiini and Perilissini. The genus Hodostates Foerster, 1869 has been revised. Work presented in this thesis is the first comprehensive comparison of both Nearctic and European species. This study resulted in the transfer of Hodostates schaffneri Hinz, 1996b to Lethades Davis.