Rhynchophorus ferrugineus is the most dangerous palm pest in Egypt and the Middle East. A lot of efforts have been made since three decades up to date to solve this problem. In this study, the essential oil of Origanum majorana was tested in vitro against larvae, pupa and adult stages of R. ferrugineus. In addition, the chemical composition of the essential oil was elucidated by gas chromatography and mass spectrometry (GC-MS) analysis. Two main toxic components (benzonitrile, 2-hydroxy 23.67%and L-linalool16.32%) were found. A significant mortalities were achieved after exposure to three concentrations (5, 10 and 15%) of O. majorana oil. Each concentration contains five replicates with 5 larva, pupa or adultfor each replicate. The effect reached 50% for 10% concentration at 96 hrs, 48 hrs and 12 hrs for larva, pupa and adult, respectively. In addition, the cuticle of treated larvae was investigated histopathologically, and corrugation and a thinning surface were found. These results suggest that O. majorana essential oil is a promising alternative to chemicalpesticides and can be used as a biopesticide against larvae, pupa and adult of R. ferrugineus.