Pereskia aculeata (Cactaceae, leaf cactus) is an environmental weed in New South Wales and Queensland. A programme was established to manage this weed in South Africa, with biological control (biocontrol) agents being released (Phenrica guerini Bechyne (Chrysomelidae)) in 1991, and (Catorhintha scaffneri Brailovsky & Garcia (Coreidae)) in 2014. With funding from the New South Wales Environmental Trust, a project was established to assess the potential of these agents for Australia. The first species imported into containment was the stem-wilting bug, C. schaffneri. Its host range was evaluated in both South Africa and Australia. A total of 39 plant species (in the families Cactaceae, Portulacaceae, Basellaceae, Didiereaceae, Aizoaceae, Crassulaceae, Aspholdolaceae, Euphorbiaceae and Caryophyllaceae), including close relatives of the target weed and agriculturally important species, were tested. Catorhintha schaffneri was able to complete development on P. aculeata, the closely related congener, Pereskia grandifolia Haworth and a dragon fruit species, Selenicereus megalanthus (K. Schum. ex Vaupel) Moran. Survival was relatively low on P. grandifolia and S. megalanthus (three and eight percent respectively, versus 78% on P. aculeata) indicating that both species might not be included in the bug’s field host range. Adult survival tests, however indicated a mean (±SE) survival time (days) of C. schaffneri on some dragon fruit species (e.g., Selenicereus monocanthus (Lem.) D.R. Hunt – 52.76 ± 7.02 and Hylocereus undatus (Haw.) Britton & Rose – 46.26 ± 12.29) was longer than on P. aculeata (43.1 ± 4.7). While the dragon fruit industry in Australia is small and specialised, its farm gate value is about $2.25 million. The potential risks posed by C. schaffneri to this industry warrants its rejection as a potential biocontrol agent in Australia. The second potential agent, P. guerini, which is nearing completion of its host-range testing, is more host-specific than C. schaffneri and is more damaging and widely established in South Africa.