"O. richmondia" normally feeds only on two endemic species of the family Aristolochiaceae, Richmond birdwing butterfly vine ("Pararistolochia praevenosa") in lowland habitats and "Pararistolochia laheyana" in highland habitats (e.g. the QLD-NSW border range national parks above 800 m) (Braby 2000, Sands and Scott 1997). Its sole non-native host plant is "Aristolochia tagala", although larvae do not transfer well to this species if already established on their usual host plants. Eggs are also laid on the introduced calico flower ("Aristolochia littoralis"), however larvae are killed by feeding on this plant. Cultivation and sale of "A. littoralis" is strongly discouraged throughout the range of the Richmond birdwing and should not be grown in Queensland at any rate, as it is also toxic to the larvae of the clearwing swallowtail ("Cressida cressida"), the red-bodied swallowtail ("Pachliopta polydorus queenslandicus") and all other Australian birdwings ("O. euphorion", "O. priamus" subspecies). The two species of "Pararistolochia" utilised by "O. richmondia" are believed to contain aristolic acids toxic to vertebrate predators.