Field evaluation studies were conducted during two years (2017/ 2018 and 2018/ 2019) to investigate the distribution and assess infestation degrees of Icerya seychellarum (Westwood) (Hemiptera: Monophellidae) on guava trees under selected prevalent climatic factors (daily mean maximum air temperature, minimum air temperature, daily mean of relative humidity and mean of dew point) at Esna district, Luxor Governorate, Egypt. The invasion of I. seychellarum was prevalent all year-round. In the first year (2017/ 2018), the population of pests formed three to four peaks (At the beginning of June, mid-September, and mid-November). Afterward, throughout the second year (2018/2019), the outbreaks of the pest were occurred in (The beginning of April, mid-June, mid-August, and mid of October). Furthermore, the percentages of infestation incidence by pests showed three to four peaks per year. With respect to climatic conditions, the autumn months during the two years were more favorable for the seasonal activity of total population density where the maximum values of infestation occurred by I. seychellarum.
             The weather factors showed an effect on pest activity and percentages of infestations during years of study which varied from year to another with an obvious to the most effective variables [daily mean maximum air temperature °C (DMaxT), daily mean minimum air temperature °C (DMinT), daily mean of relative humidity % (DRH%), and mean of dew point ° C (MDP)] for these changes for both years.