Ecological studies of citrus leaf miner (CLM) Phyllocnistis citrella were carried out in citrus orchards at three different Agro-ecosystems namely Clalyoubia, Sharkia and Beni-Sweif for three successive years 1996, 1997 and 1998. For Qalyoubia Governorate CLM, infestation started to appear in new shoots as early as mid April, 1996 and three weeks later for both 1997 and 1998 (i.e. May 5th). The CLM infestation disappeared during the 1st half of December. Seven field generations were completed during citrus flushing periods. For Sharkia Governorate, the main period of activity was extended between the 2nd week of May and the last week of December, thus demonstrating 9 generations. Thus for Beni-Sweif Governorate, however, young citrus trees the infestation high figures revealed possibly all the year round. Samples were picked comparatively and 10 annual generations were recorded in navel organ leaves. Navel orange was the most preferendum species for citrus CLM infestation and the most susceptible compared with other citrus varie­ties throughout the three successive years. Lime variety ranked second, while mandarin variety was the least.