in the present study the population fluctuation and host preference of the tomato leaf miner Tuta absoluta (Meyrick), a dangerous pest attacking Solanaceae in Egypt causing great losses, was investigated using pheromone traps. The study was conducted in Kafr El Sheikh Governorate. The incidence of the pest was studied in two important vegetable crops, i.e. tomatoes and eggplants. Pheromone traps were used to capture males of T. absoluta in two different locations per crop. Number of moths was recorded through a period of 4 months starting from October 2016 till January 2017. Degree Days Unit was estimated during the period of the research, in addition, temperature, relative humidity and wind velocity effects on the pest population fluctuation was investigated. Moreover, the effect of the pest on the economic indicators of tomato crop was also studied. T. absoluta registered 4 peaks in both crops, prefers tomato as a primary host plant and is active within the range of 10-20◦C. Relative humidity did not affect the pest population either in tomato or in eggplant within the period and location of the experiment whereas wind velocity showed a direct effect. Males' captures increased when wind velocity ranged between 40-58 Km/hr. Results indicated that the loss in production of tomatoes in Kafr El Sheikh Governorate reached 17.2 thousand tons, while on the country level it reached about 571.8 thousand tons, which equivalent to 26.7 and 880.6 thousand pounds on both levels, i.e. Kafr El Sheikh and country, respectively. The economic evaluation analysis indicated that on the 4th and 5th weeks of tomato transplanting; control measures intensity should be condensed to decrease the rate of pest infestation in tomato fields.