A field experiment in bitter gourd with sorghum as border crop was carried out to conserve and enhance the parasitoid Aprostocetus diplosidis population to manage gall midge in bitter gourd. Two fields were selected for the experiment one without the border crop and another with border crop of sorghum. During the cropping season both the fields were observed at periodic intervals for the adult parasitoid activity and percent parasitization of bitter gourd gall midge. In both the fields, the parasitization percent was not significantly different during the earlier cropping period of bitter gourd up to eight weeks of sowing. From ninth week of bitter gourd cropping co-existed with 90 days old ear head bearing sorghum as border crop, resulted in with the escalation of adult parasitoid activity A. diplosidis and parasitization percentage of bitter gourd gall midge. Due to emergence of parasitoid A. diplosidis on Contarinia sorghicola as alternative host on completion of each successful generation, of the A. diplosidis the percent parasitization of gall midge showed double fold increase in bitter gourd. Subsequently, at the ends of bitter gourd cropping season, the A. diplosidis parasitization reached 48.4 per cent. The result indicates that maintenance of ear head bearing sorghum as border crop throughout the cropping period of bitter gourd could achieve maximum parasitization of gall midge Lasioptera spp.