An effective lure-and-kill trap is a potentially important instrument in monitoring and controlling oriental fruit ßies, Bactrocera dorsalis (Hendel). A number of experiments were performed in an orchard of commercial guava, Psydium guajava L., to determine how ßy captures are affected by combining visual and olfactory stimuli, and by the timing of trap deployment relative to host phenology. Baiting sticky Ladd traps with hydrolyzed liquid protein signiÞcantly increased the number of captured

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... es. Mostly male ßies were caught in the absence of mature guava fruit, whereas mostly female ßies were caught when ripe fruit was abundant. These results suggest that an effective oriental fruit ßy 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 ßy populations.