Abstract
myiasis caused by nasal sheep fly Oestrus ovis L. is one of the most parasitic infestation of wide pre valence all over the world, it is considered as health problem in Ramadi city sheeps, this study aimed to know the life cycle of this insect inside and outside the host during the period (April 2019 to March 2020) by examining (180) sheeps heads that were slaughtered in Ramadi butchery using special questionnaire prepared to records morphological internal information’s including ( head color, age, gender ,sample collection date and presence of larval instars inside nasal pockets.
The results reveals that The total infestation rate in sheep was (57.7) %, and according to year seasons (winter (42.2) %, spring (51.1) %, summer (60) %, and autumn (80) %)respectively and the percentage of transformed larvae to adult stage were (31.1) % was recorded in the summer, autumn, and spring (35.7) % and (34.7) %, respectively. It reveals also that females was more infected with larvae than male (70.7, 41.9) % respectively, high infection appeared in sheeps of more than one year old compared with those of less than one year old (68.3 , 25) % respectively. The rate of infection in sheep. Heads according to the color was (67.3 , 56.7 , 48.9) % in black ,blond (red) and white color respectively .

Key words: myiasis, sheep nasal fly , Oestrus ovis , Oestiridae