The oystershell scale insect, Lepidosaphes ulmi (L.) is considered one of the serious pests attacking olive trees in Egypt. The present study was carried out in Naser region, Beni-Suef Governorate during two successive years (2021 and 2022). The population fluctuation of the oystershell scale showed two to three peaks that were recorded during the spring, summer and autumn seasons during the years of study. The highest population peak was recorded in summer (11 and 15.6 insects/leaf, through 2021 and 2022, respectively). While the percentage of parasitism showed 4-5 peaks annually. The factors of minimum and maximum temperatures, relative humidity, and parasitism had non-significant effect on population density of L. ulmi in 2021 season, but had highly significant effect in 2022 season. However, these ecological factors had significant effects on the parasitism rates in both years of study.The parasitoids, Aphytis chrysomphali and A. diaspidis (Hymenoptera: Aphelinidae) were collected from L. ulmi scales.