Abstract
Seasonal changes in numbers of the melon fly, Dacus cucurbitae COQUILLETT, have been investigated by counting numbers of males caught in Cue-lure bait traps on Kikai Is., Kagoshima Pref. since 1974 when the species had first invaded the island. Total numbers of annual catches rapidly increased in 1976 and 1977, and such high density as over 10, 000 males per 50 traps in 1977 was considered to be related to richness of Diplocyclos palmatus C. JEFFREY (Cucurbitaceae). In general, there was a tendency for the melon fly population to increase in autumn and to decrease remarkably in winter. Relative abundance of the melon fly was also investigated in 1977 at several different habitats on the island. The melon fly was most abundant in isolated groves, and it was low in number inside villages. These differences in the relative abundance cannot be ignored for estimating and controlling the population density of the species in the future.
