Aphid species and their natural enemies were identified in a citrus orchard in the Cap Bon region of Tunisia in 2014–2016. Aphids within the same orchard had previously been studied in 1991–1992, allowing a comparison of the populations over the 20+ yr. Ten aphid species were identified in 1991–1992, while only four were observed in 2014–2016. This reduction in aphid diversity could be linked to observed temperature and rainfall changes attributed to climate change, interspecific competition, increased occurrence of hyperparasitoïds, or any combination of these and other factors. Aphis spiraecola Patch and Aphis gossypii Glover increased in abundance and occurrence, which is of special concern because they are known as vectors of Citrus tristeza virus. Four species of parasitoids and two of predators were identified in 2014 samples, while an increase of hyperparasitism occurred.