Absence of the natural enemies that limit their populations in their areas of origin generally explains the propagation of invasive plants. Few associations are known between invasive plants and insects at Réunion Island. There, in infested indigenous ecosystems, 42 phytophagous insects (Coleoptera, Diptera, Hemiptera, Lepidoptera and Phasmida), among which 19 are endemic of one or several Mascarene Islands, have been recorded on 20 non-native invasive plant species. Among the 220 associations with invasive or indigenous plants 147 were not recorded before. Lepidoptera and Coleoptera form the predominant insect groups. Lepidoptera include several families : Crambidae, Geometridae, Hesperiidae, Noctuidae, Nymphalidae, Sphingidae, whereas Coleoptera (14 species) are mainly Curculionidae with 13 recognized weevil species. The host range spectrum is very broad for the greatest part of collected insects. The endemic species of Geometridae are essentially associated with endemic plants (39% of records) while the species with a broad distribution are mainly recorded on invasive species. The Geometridae family is more closely associated with endemic plants than Noctuidae and Curculionidae ; while the Noctuidae with a broad distribution are more closely associated with alien plants (30% of the records) than Geometridae and Curculionidae (respectively 7% et 4%). Some endemic polyphagous Curculionidae are also associated with invasive (14%) or non-invasive (8%) exotic plants. These significant differences are mainly explained by the very nature of the diet. Although leaf-eating insects (sphingids, noctuids and phasmids) induce some damages to invasive alien plants, these are insufficient to reduce the density of these pests ; damages by flower-and particularly seed-feeder insects would probably be more efficient but this needs further research.