The physiological state of an insect is likely the most important endogenous factor influencing resource-oriented behavior, and it varies considerably among individuals. Trials were conducted in mango orchards to study the effect of multiple endogenous biological factors on the response of two fly species, Anastrepha ludens (Loew) and Anastrepha obliqua Maquart (Diptera: Tephritidae), to BioLure and NuLure baits. The biological factors of the two fly species that were tested were the following: 1) fertility status—sterile (irradiated) and fertile flies; 2) two types of diets (only sugar and a 3:1 mixture of sugar and hydrolyzed yeast protein; 3) sex, and 4) two sexual maturity conditions (2–4- and 15–18-d-old flies, representing immature and sexually mature flies, respectively, and 2–4-d-old flies treated with methoprene as an artificially induced sexually state male condition). The laboratory-treated flies were released into three different mango orchards. The trials were conducted in four blocks per orchard using eight traps in each block (50:50 BioLure: NuLure). The traps were replaced every 2 d during the 12-d period and the flies per trap per day values were calculated. More protein-fed, fertile, female, immature, and A. obliqua flies were caught compared with the other flies tested. In addition, the traps baited with NuLure attracted more flies than those baited with BioLure. Interaction analyses indicated that the type of bait and the sexual maturity status were the most important factors affecting the responses of the flies. Our study demonstrated that lures attract only a small segment of the fly population, those that have a specific hunger for amino acids—immature flies—and those that were protein-starved. The implications for improved trapping system designs are discussed.