An effective lure-and-kill trap is a potentially important instrument in monitoring and controlling Oriental fruit flies, Bactrocera dorsalis(Hendel). A number of experiments were performed in a commercial guava (Psydium guajava L.) orchard to determine how fly captures are affected by combining visual and olfactory stimuli, and by the timing of trap deployment relatively to host phenology. Baiting sticky Ladd traps with hydrolyzed liquid protein significantly increased the number of captured flies. Mostly male flies were caught in the absence of mature guava fruit, while mostly female flies were caught when ripe fruit was abundant. These results suggest that an effective Oriental fruit fly trap should include both visual and olfactory lures, and that proper timing of trap deployment can be an important factor in monitoring female abundance in Oriental fruit fly populations. [Full Text]