Ecological studies had been carried out in cotton plants to investigate the population density and effect of certain weather factors on the two-spotted spider mite, Tetranychus urticae Koch; Phytoseiulus persimilis, and Tarsonemidae. and some insect predators, Stethorus gilvifrons (Mulsant), Orius insidiosus and Chrysoperla carnea (Stephens), in two successive seasons, 2021 and 2022 at Mansoura district. There were two peaks in 2021 for T. urticae whereas three peaks in 2022. That highest peak was found in 2021 during the first week of July (1040 individuals /25 leaves), while that was in the last week of July (1043.3 individuals / 25 leaves) in 2022. The results indecated that P. persimilis had first seen in the second week of May in both seasons of the study. The highest peak was found during the second week of Jun (5.5 individuals /25 leaves) in 2021, but, in 2022, that was in the first week of July (4.0 individuals / 25 leaves). In addition to that, family Tarsonemidae was first seen in the second week of May 2021 and 2022. It recorded two peaks in 2021 and one beak in 2022. These peaks were found in the first and second week of July recording (2.3 individuals) in 2021. The beak in 2022 was at the last week of July with the same density as 2021 (2.3 individuals). Predatory insect S. gilvifrons had one peak in the 2021 whereas two peaks in 2022. The highest density was found during the first week of July (5.8 individuals) in 2021. While, O. insidiosus had only one peak in each season of the study, the highest density was in 2021 at the first week of July (6.0 individuals). C. carnea was first seen in the first week of May during the two seasons of the study. It recorded one peak in both seasons. 2022, recorded high density in the third week of July, (5.5 individuals). The statistical analysis showed that there was no significant correlation between most pests and temperature parameters in 2021. both T. urticae and Tarsonemidae there was positive significant for both maximum and average temperature in 2022. While a slight negative effect in 2021 for P. persimilis. a moderately significant correlation between the average temperature and the number of S. gilvifrons during the season of 2022. The statistical analysis showed that there was a highly significant positive correlation between the temperature parameters and the number of O. insidiosus during the season of 2022. While C. carnea had a non-significant correlation with temperature parameters in the two seasons of study.