Mated female papaya fruit flies,Toxotrypana curvicaudaGerstaecker, oriented to and contacted single immature papaya fruit presented in an experimental arena and exhibited a rhythmic up-and-down movement of the head (bobbing) after initial contact with the fruit. Such bobbing, with the proboscis contacting the fruit surface at each bob, always preceded probing and puncturing of the fruit with the ovipositor. Forty-eight percent of 25 females tested probed within 5 min; 11 of these laid an average of 29 eggs per oviposition bout, which lasted an average 20.5 min. Withdrawal of the ovipositor was followed by ovipositor grooming and extensive continuous sponging of the fruit surface with the proboscis. During observations of female papaya fruit flies on fruit in a commercial papaya planting, all of these types of behavior were observed. Using the same laboratory experimental design, a combination of color (green), shape (wax disks and domes), and chemistry (solvent extract of papaya peelings) was required to obtain rates of contact similar to those obtained with immature fruit. However, oviposition was not obtained using such combinations of artificial stimuli. In a flight tunnel, mated females were attracted to immature papaya fruit and to the odor of papaya fruit piped into the tunnel indicating that host odor is used in long-range orientation to host plants and fruit.