Pre-monsoon studies were conducted to study the variation in Drosophila population in Karapuzha dam backwaters, Waynad, Kerala. A total of 825 Drosophila flies belonging to eight species of three subgenus
namely, Sophophora, Drosophila and Scaptodrosophila were collected. Subgenus Sophophora waspredominant with six species and Subgenus Drosophila and Scaptodrosophila was least represented with
one species each. The diversity of Drosophila community was assessed by using Simpson, Berger-Parker and Shannon-Wiener indices. Simpson index was low at 0.1704 in the region adjacent to lake when
compared to other regions, which indicates high diversity. This can be attributed to the moist environment and vegetation near the lake. Cluster analysis and Occurance constancy method was used to analyze the
species occurrence. The distribution pattern of Drosophila was uneven in space and time.
