One of the most serious mealybug species that attack guava tress in Egypt is Icerya seychellarum (Hemiptera: Margarodidae). This study has been done to monitor the fluctuations in population of this pest in guava orchards during seasons of 2018/2019 and 2019/2020 in new Damietta district. The effects of abiotc (temperature and relative humidity, preferable direction) and biotic (predators) factors on its population has been examined. Three annual peaks of seasonal abundance for I. seychellarum were determined during November, May and September. The highest population of this insect was recorded during autumn season with total numbers of 1957 and 1674 individuals/leaf during the first and second year, respectively. On contrary, the lowest population of I. seychellarum was recorded during spring seasons of both years. The metrological factors insignificantly affected on the total population of the tested pest. The north direction is the preferable direction for I. seychellarum during the two years of study. Data revealed that there was synchronization in occurrence between populations of I. seychellarum and its predators, Rodolia cardinalis and Chrysoperla carnea.