Biodiversity,taxonomical and population genetical studies have progressed little due to lack of interest of people in it. Although many workers feel that the taxonomical work shall not be neglected, people show little interest because of the hardship during work and lack of opportunity in the field. To fill up this gap at least partially, the present work is carried out. One year long study was conducted to analyze the altitudinal and seasonal variation in population of Drosophila in Chamundi hill of Mysore, Srirangapatna, Krishnarajasagar and Talakadu of Karnataka State, India. A total of 16,671 Drosophila flies belonging to 20species of 4 subgenera were collected from 680m,780m and 880m and 980m altitudes this is highest figure compare to other three localities. It was noticed that the subgenus Sophophora was predominant and subgenus Drosilopha was least represented with only single species. Cluster analysis and constancy method along this some indices were applied to analyze the species occurrence qualitatively.The study shows that the distributional pattern of a species or related group of species is uneven in space and time.