Some invasive plant species are used by native wildlife but may also be subject to control measures motivated by habitat conservation or restoration. If rare, threatened, or endangered species benefit from an invasive species, how can land managers balance conflicting conservation directives? In this study we investigated the use of Nicotiana glauca, a noxious weed, by Manduca blackburni a U.S. federally listed endangered moth. We surveyed N. glauca for immature stages of the moth at two locations on Hawaiʻi Island, Hawaiʻi, over a three-month period. Plant height and leaf density were estimated and Pearson c2 tests were used to understand oviposition preference in relation to those factors. Blackburn’s sphinx moth preferred plants >2 m tall with medium and high leaf density. In contradiction to the typical response of native insects to invasive plants, this endangered moth is now almost entirely dependent upon an invasive weed for survival. By identifying preferred characteristics of invasive host plants, land managers may focus removal efforts and minimize resource loss for imperiled species dependent upon them.