The melon fly, Dacus cucurbitae Coquillett, was eradicated from the 33-sq-mile island of Rota, M. I., by the release of 257 million flies irradiated as pupae with 9.5 kr from a cobalt 60 source. Pupae were produced in Hawaii and air shipped 3800 miles. Releases were made from both air and ground at weekly intervals between September 1962 and July 1963. They were preceded by low-cost applications of concentrated protein hydrolyzate-malathion bait sprays, limited to about 20 of the principal flyproducing sites. Predators, off-island drift, and shorter life of boxed flies reduced the efficiency of the releases. Fruit infestations disappeared late in December 1962 and none occurred in 1963. Sterile eggs were found until the end of February 1963. Sterile flies of both sexes congregated in host plantings, the same as wild flies, but sting damage by females was far less per female than by wild individuals. Some sterile flies of each sex lived 4 months after the last release.