ABSTRACT
The project to eradicate the melon fly, Bactrocera cucurbitae, using sterile insect technique from Okinawa Prefecture was begun in 1972, and it was successfully achieved in 1993. Information on the flight ability and on the direction of movement of flies is necessary to evaluate the possibility of re-invasion of the flies. The flies were captured in the coastal regions of the northern part of the Okinawa Islands in the summer, fall and winter. An environmental factor that may have influenced the movement of the flies is wind. The melon fly may have expanded its distribution to the north by wind-assisted flight. Considering the flight ability of melon flies, this rapid northward spread might have been by natural flight. Once the flies became established on an island, they could then rapidly expand their range to adjacent areas.
