Effectiveness of GF-120 (Dow Chemical) Fruit Fly Bait containing the insecticide spinosad in controlling mango-infesting fruit ßies (Diptera: Tephritidae) was assessed by comparing treated orchards with untreated orchards. Twelve mango, Mangifera indica L., plantations located in six villages (two similar orchards per village: one orchard treated and orchard untreated) scattered in the Borgou department (northern Benin) were monitored weekly with ßy traps, and the fruit was sampled twice for larval infestation at the beginning and in the middle of May in both 2006 and 2007. The two main mango fruit ßy pests are Ceratitis cosyra (Walker) and Bactrocera invadens Drew, Tsuruta & White, an invasive species that recently spread throughout West Africa. In both the 2006 and 2007 seasons, C. cosyra had the earliest peak of abundance, and the difference between treated and untreated orchards, in terms ofmeannumber of ßies trapped per week and per trap, was signiÞcant only in 2007. B. invadens populations quickly increased with the onset of the rains, from mid-May onward, with no signiÞcant difference between treated and untreated orchards. In 2006 and 2007, the larval infestation by B. invadens was signiÞcantly lower in plots treated with GF-120 than in untreated control plots. GF-120 provided an 81% reduction in the number of pupae per kilogram of fruit after weekly applications for 7 wk in 2006 and an 89% reduction after 10 wk of weekly applications in 2007. The possibility of integrating GF120 bait sprays in an integrated pest management package is discussed in relation to market requirements.