Distribution of the melon fly,Dacus cucurbitaeCoquillett, was determined by trapping males at 330 sites throughout the island of Kauai. Melon flies were most numerous at coastal trap sites, particularly along the south and west coasts. The Waimea Valley site located on the southwest coast was the one with the highest trap catch. Lowest catches were made at the highest elevations at the center of the island. Trap catches declined sharply with increasing rainfall and increasing elevation. However, during the seasonal peak in abundance in late summer, a few flies were trapped in the higher elevations where no host plants were present. These flies were evidently migrating rather than breeding flies. Melon fly distribution was related to distribution of its host plants. Distribution of the fly was largely along coastal areas of the island where host plants were present in commercial and backyard gardens. The melon fly was also present in noncultivated areas where the wild host,Momordica balsaminaL., was located along edges of fields and roadsides.