Introduction. Fruit flies contribute significantly to yield losses experienced by citrus farmers in Nigeria. The majority of farmers have meager resources and limited knowledge of appropriate citrus pest management strategies. The best alternative for them is the application of control methods that are environmentally friendly and affordable. Our work was therefore designed to develop baits from a cheap source for monitoring fruit fly populations and controlling them while minimizing environmental hazards. Materials and methods. Protein bait prepared locally from brewery yeast waste by the process of heat autolysis was compared with the imported protein hydrolysate bait in McPhail traps. These traps were hung on the trees of four sweet orange varieties during the major citrus fruiting seasons of 2003 and 2004. Results. Species of Ceratitis dominated in the fruit fly samples collected. Both the imported and locally made baits caught significantly higher numbers of fruit flies than the non-baited control. There was no significant difference between the populations of fruit flies caught by the two baits during the studies. The decreasing order of varieties according to trapped fruit fly numbers for both the imported and locally made baits were: Washington navel > Parson Brown > Valencia late > Agege-1. The fruit fly numbers observed on Washington navel were significantly higher than those of Agege-1 and Valencia late. Discussion. Our results show the effectiveness of the locally made protein bait in fruit fly monitoring and management. Varietal differences also played a part in determining the extent of fruit fly attacks on sweet oranges.