Aim of study: To survey and report the behavior of the weevil Pleurodirus fairmairii as a pest species on Cistus heterophyllus subsp. carthaginensis (Pau) M.B. Crespo & Mateo (Cartagena’s rockrose), in order to provide the first biological data on this species. Cartagena’s rockrose is an Ibero-Balearic endemism considered as "endangered" in the Spanish Catalogue of Threatened Species. Its current distribution is limited to the Spanish provinces of Murcia, Valencia and the Balearic Islands. Area of study: The study has been conducted in Valencia province (Spain). Material and methods: Pleurodirus fairmairii was observed in the field feeding voraciously on Cartagena’s rockrose. Damages were described, and several individuals of the weevil were captured alive for preliminary observation of their feeding habits under laboratory conditions. The trials (no-choice test) consisted of offering a freshly plucked leaf from different potential host plants to the weevils introduced individually in a Petri dish. Furthermore, a male and a female were dissected for the study of genitalia, and their respective components were prepared for microscopy study and subsequently described. Main results: This paper reports for the first time the occurrence of the weevil Pleurodirus fairmairii on plants of C. heterophyllus subsp. carthaginensis and describes the important damage it causes on leaves, stem, buds, flowers and fruits. Research highlights: A short description of the adults is given, including the genitalia, that are shown and described for the first time.