Introduction. Damage caused by tephritid fruit flies has been identified as a major limiting factor to citrus production in Nigeria. Presently, no control measure is applied by the majority of the farmers. This study therefore seeks to evaluate the efficacy of locally-made protein bait sprays and the differences in the susceptibility of sweet orange varieties in reducing fruit fly damage. Materials and methods. In 2006 and 2007, one, two and three spot applications of locally-made protein bait mixed with chlorpyrifos insecticide were administered to Agege, Parson Brown and Valencia Late sweet oranges. Treatments were arranged in a randomized complete block design. Efficacy of the bait sprays in reducing fruit attack was assessed by randomly sampling 10 ripe or ripening fruits per stand as well as dropped fruits. Results and discussion. The bait sprays significantly (p < 0.05) reduced damage of sweet orange by lowering the infestation level of Bactrocera invadens Drew Tsurata & White, and consequently reducing the number of dropped fruits. Application of three spots of bait was most effective in reducing damage due to B. invadens on sweet orange varieties. The infestation level of B. invadens and the number of dropped fruits of the variety Agege were significantly (p < 0.05) higher than those of the varieties Parson Brown and Valencia Late. Conclusion. Our study shows that three spot applications were most efficacious in reducing fruit damage, and that the Valencia Late variety was the least damaged, followed by Parson Brown.