On south-west Indian Ocean islands, many crops and ornamental plants are threatened by the spiralling whitefly Aleurodicus dispersus (Hemiptera: Aleyrodidae), which is a polyphagous pest that is native to the Caribbean region. Aleurodicus dispersus causes economic damage to various crops on all the islands in the south-west Indian Ocean. The hymenopteran parasitoid Encarsia guadeloupae (Hymenoptera: Aphelinidae) is a natural enemy of A. dispersus on the Caribbean islands. In this study, we assessed the geographical distribution of the parasitoid in La Réunion, an island in the south-west Indian Ocean where the parasitoid was first observed in 2004. We also investigated its main life-history traits. Field surveys indicated that the parasitoid is widespread in most of the low-lying areas of the island and exhibits high parasitism rates on A. dispersus populations. At 25°C, E. guadeloupae adults had a mean longevity of 33.6 days, and its pre-imaginal development required 23 days. The lower temperature threshold and thermal constant were estimated to be 7.9°C and 132 degree-days, respectively. Females of E. guadeloupae preferred to deposit eggs in early rather than in late instars of A. dispersus, and oviposition rates were highest in the second larval instar. Females of E. guadeloupae were able to oviposit in larvae of other species of whiteflies found in La Réunion (Bemisia tabaci and Dialeurolonga simplex), although subsequent development of the parasitoid was not monitored. Finally, we discuss the potential use of E. guadeloupae for the control of whitefly populations on islands in the south-west Indian Ocean.