An experiment was carried out at the Agricultural Research Sta­tion, Kafr El-Sheikh, to study the larval population of Liriomyza congesta (Beck.) on faba bean plants and its relation to certain weather factors (weekly means of temperature and relative humidity) as well as the number of its generations during 1991/92 and 1992/93 seasons. Weekly mean numbers of live larvae of L.congesta revealed that larval population was lower during 1991/92 than 1992/93. Three popu­lation peaks were observed and three generations of larvae took place between December and April. For both seasons of investigation, the highest peak occurred by March 9. Weekly means of temperature exhibited positive correlation with larval population during both seasons, but the effect of the same weath­er factor was insignificant during the first season and highly significant during the second one. On the other hand, relative humidity induced negative and insignificant relationship during both seasons. The com­bined effect of the two considered weather factors was more pro­nounced on larval population during the second season as it was respon­sible for 73.90% of the changes in population in 1992/93 compared to 58.53% in 1991/92.