An ambitious attempt was made over the period from 1972 to 1993 to eradicate the melon fly, a pest species that invaded Okinawa, Japan, around 1919, using the sterile insect technique (SIT). With every intellectual and technical effort, and after releasing about 50,000 million sterile flies, this pest was completely eliminated. The key points for the successful eradication were: (1) determining the number of sterile flies to be released in accordance with the estimated density of wild flies and with the aid of the special population models; and (2) conserving as many genetic characteristics of wild strain as possible in mass-rearing. Importance of basic studies, especially of ecology and mating behaviour of the target species is discussed.