The recently introduced oriental fruit fly Bactrocera dorsalis is not the only important pest of mango in Réunion, where the plant bug Orthops palus remains the most concerning pest of the flowering stage of this fruit crop. In anticipation of the phase-out of synthetic insecticides targeting this pest, the potential of alternative control pathways is being investigated. One pertains to the encouragement of conservation biological control by another plant bug species occurring on mango inflorescences, Campylomma leucochila. This bug is generally considered as a predator, rather than a mango pest, notably based on an earlier preliminary dual stable isotope analysis (15N and 13C) of insects associated with mango inflorescences. To verify these results, we sampled during 2019 and 2020 mango flowering seasons, in and around a mango orchard at Bassin-Plat (Saint-Pierre), plant bugs (Hemiptera: Miridae) on mango and rattlebox Crotalaria trichotoma, a cover crop that was earlier found to shelter significant populations of C. leucochila. Results of 15N and 13C analyses showed that on mango inflorescences, both plant bug species belonged to the same omnivorous group, while on rattlebox, C. leucochila belonged to the same trophic group as Moissonia importunitas, a strictly herbivorous plant bug restricted to a few legume species (mainly rattlebox and white lupin). These results question the status of C. leucochila as a predator of O. palus. Depending on the plant, it can even be merely herbivorous, while conversely, O. palus could be more omnivorous than merely herbivorous. In view of the biological control of O. palus in Reunionese mango orchards, the predatory status of other arthropods should be investigated, along with that of parasitoids, since entomopathogenic biological control could negatively interfere with Sulphur spraying, which is now the only available option for dual management of mango powdery mildew and plant bugs.