A field study was carried out at the experimental farm of the faculty of Agriculture, Kafr EL-Sheikh region during two successive seasons 2014 and 2015, to study the population fluctuation of Tuta absoluta larvae and associated predators  on tomato plants and determine the effect of some insecticides and biocides on T. absoluta larvae and chlorophyll content in tomato leaves., Also, Relationship between numbers of insect males caught in pheromone traps and its larvae. Results showed that in the first season 2014, T. absoluta larvae appeared in relatively low numbers and increased gradually to exhibit the two peaks (187 and 168 larvae /10 plants on June 24^th and July 15^th, respectively. The same trend was recorded in the second season 2015. As for predators, Nesidiocoris ternuis constituted the greatest in number followed by true spiders. coccinella undicimpunctata (L.) came in the third rank, while Scymnus spp. was recorded in few numbers. Results indicated that Excellent insecticide was the most potent compound in reducing the population density of T. absoluta larvae with reduction of 90.97, 95.67, 96.26% after application at 5, 7 and 10 days, respectively. with  all average 94.2+1.6 of reduction  While the least average of percentage of reduction for insect larvae caused by Biotect 48, 41, 86.43 and 85.40% at 5, 7 and 10 days after application, respectively with the least average 71.7+11.7. In the second season 2015, in contrast, Voliam flexi was the most potent compound in reducing the population density of insect larvae with reduction percent of 100.0, 98.1 and 100.0% at 5,7 and 10 days after application respectively, with  all average 99.2+0.8 .While Agree compound  caused the least average of reduction for insect larvae with 81.5, 78.88 and 84.5% at 5, 7 and 10 days after application respectively with  all average 81.6+1.6. Statistical analysis showed significant differences among treatments to reduction of T. absoluta larvaein the first and second seasons. Chlorophyll content grand average increased by Biotect treatment while it was least with Voliam flexi in 2014 and 2015 season. Populations of T. absoluta males appeared in sex pheromone traps had three and four peaks in 2014 and 2015 seasons, respectively, while larvae of this insect had two peaks and one peak in the first and second season, respectively.