A biological control program has been initiated against the European swallow-worts Vincetoxicum nigrum (L.) Moench and V. rossicum (Kleopow) Barbar. (Family Apocynaceae) that have become invasive in North America. The leaf-feeding moth, Hypena opulenta Christoph (Lepidoptera: Erebidae), originating from eastern Europe, has been under measurement as a potential biological control agent of swallow-worts since 2006. In this study we measured the host range of H. opulenta by screening 82 potential host plant species for larval development under no-choice conditions. In addition, we also monitored female fecundity, longevity, and oviposition preference among suitable larval hosts. Successful larval development occurs only on Vincetoxicum spp. Partial larval development by one larva was observed on Boehmeria cyclindrica (L.) Sw. (Urticaceae) to the final instar, but this individual failed to pupate. Exploratory feeding occurred on Gonolobus stephanotrichus Griseb. (Apocynaceae) and Urtica dioica L. (Urticaceae), but all larvae failed to develop past the first and second instar, respectively. Additional testing with mature larvae on a subset of the plant species demonstrates that no species outside the genus Vincetoxicum are suitable for complete larval development of H. opulenta. The longevity and fecundity of females raised on each target weed are similar and gravid females do not display an oviposition preference among Vincetoxicum spp. Hypena opulenta does not present a risk to any native plant species or species of economic importance in North America. Petitions have been submitted for experimental open-field releases of H. opulenta in the United States and Canada.