The present investigation was conducted during 2018/2020 seasons inMenoufia governorate, to study the effect of three faba bean varieties, weather factors and three levels of fertilization on the population density of Liriomyza trifolii L. The obtained results stated that the population density recorded two peaks during the first season (2018-2019) on Misr1 and Misr 2 varieties, while three peaks on Giza 843. During the second season (2019-2020) three peaks of abundance occurred on Misr1 and Giza 843, while on Misr 2 occurred four peaks. The larval population reached the highest value of 40.9, 54.4 and 59.8 larvae/leaf (1^st. season), while in the second season recorded 37.1, 37.7 and 47.5 larvae/leaf for the three varieties, Misr1 and Misr 2 varieties and Giza 843, respectively. The highest infestation percentage was recorded100% in 1^st. season, while in 2^nd season recorded 100, 98.4 and 92.3% on the three varieties, respectively. Data obtained revealed no significant differences between the three varieties when fertilized with the three levels, while significant differences were recorded between Misr 1and Misr 2 compared with Giza 843variety during both seasons of study.