The Mediterranean pine engraver, Orthotomicus erosus (Wollaston) (Col.: Curculionidae: Scolytinae), is a destructive bark beetle in pine forests worldwide. Regarding the recent outbreak of O. erosus in Iran, its flight activity and population density were monitored in four contaminated sites in western Tehran. These four sampling sites included Tabiat Park, Khargush Darreh Forest Park, Chitgar Park behind Bam Riding Club as well as Chitgar Park 9th Aghaghiya Street (western Tehran). Two pheromone traps (ECONEX ORTHOTOMICUS EROSUS 60 DAYS pheromone, Spain) were installed in each sampling site at the height of 2.5 m in the south direction of the pine trees. The number of trapped adults was recorded at 10-day intervals from April 2019 to March 2020. In total, 8514 adults of O. erosus were collected using pheromone traps during the sampling period. The results showed that the adult flight started from April in four sampling sites. The flight periods of adults continued until November in Tabiat Park, Khargush Darreh Forest Park, and Chitgar Park, behind Bam Riding Club. Differently, the last adults were collected in October in Chitgar Park, 9th Aghaghiya Street. In addition, the flight peaks of O. erosus occurred in August in Tabiat Park, Khargush Darreh Forest Park, and Chitgar Park, behind Bam Riding Club. However, the highest number of adults were trapped in July in Chitgar Park, 9th Aghaghiya Street. Based on our results, the number of trapped adults was significantly different in sampling sites. The mean number of trapped adults was the highest (183.25 ± 0.11) in Chitgar Park, 9th Aghaghiya Street and lowest (106.32 ± 0.07) in Tabiat Park during the whole monitoring experiment. These findings on flight activity and population fluctuation of O. erosus in local conditions could be helpful to establish an efficient and successful management program for this destructive pest
