Research on fruit flies in melinjo plants in Indonesia has been carried out but will only be limited to locations on the island of Java, so it is necessary to prove whether fruit fly species that attack melinjo in South Kalimantan are the same or different from the results of previous studies. The locations chosen for this study were Damit Village, Batu Ampar Sub-district, Tanah Laut Regency has many melinjo plantations which are attacked by fruit flies; therefore, it is necessary to identify the species of fruit flies and to find out the abundance and sex ratio of the species population. The study was conducted by collecting the attacked fruit from five different points and putting the fruit in jars filled with wood sawdust. The results of the identification showed that the fruit flies that attacked melinjo fruit was Bactrocera mcgregori. The highest abundance of B. mcgregori was 75.6% and the lowest was 8.4% with an average of 37.06%. The highest sex ratio of B. mcgregori was 0.88 and the lowest was 0.61 with an average of 0.78. The attack of B. mcgregori fruit flies on melinjo fruit was the first report in South Kalimantan.