Fly densities were estimated in four selected localities of Qaluobiya Governorate using sticky traps. Files could be collected during all months of the year; however, population densities were fluctuating. Maximum and Minimum fly abundance occurred at approximately the same time at all sampling localities. Musca domestica was the most common fly species in both urban and rural areas of the Governorate. The distribution of fly population between outdoor and indoor sites was also studied.