Ecological studies of citrus leaf miner (CLM), P. citrella. were carried out in citrus orchard at Faculty of Agriculture, Al-AzharUniversity. All citrus cultivars are variously attacked by such pest. This study was carried out on navel orange, lime and mandarin, through two successive years (2006 and 2007). The most susceptible species was navel orange and lime, while the least species was mandarin. The infestation in the two years, started in the first week of May, until the end of the first week October. The infestation in the second year (2007), was higher than the first (2006). In the first season (2006), the population was fluctuated and showed five to seven peaks. The  highest peak on navel orange, lime and mandarin, was 192, 162, 73 insect /50 leaves respectively, in 30th of July. While in the second year (2007), the population also had five to seven peaks, the  highest peak on navel orange, lime and mandarin, was 214, 192, 88 insect /50 leaves respectively, on 29th of July. In the first year (2006), all abiotic factors (daily max. temperature, daily min temp. and daily mean temp.) had a positive and highly significant effect. While relative humidity had a negative and insignificant effect, on population. The biotic factors (parasites) in the same season gave a positive and insignificant effect. In the second year (2007) daily max. temp., daily min temp. and daily mean temp. had a positive highly significant effect. The effect of relative humidity was a negative and insignificant, while the parasites had a positive and insignificant effect. The combined effect of all factors was 75.66 in 2006 and 65.66% in 2007. The population of CLM preferred the eastern and southern than the westren and northern directions of the trees.